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127-467: Jotnian sediments include quartz -rich sandstones , siltstones , arkose , shale and conglomerates . The characteristic red colour of Jotnian sediments is due to their deposition in subaerial (e.g. non-marine) conditions. Jotnian sediments are the oldest known sediments in the Baltic area that have not been subject to metamorphism . Their age is poorly constrained, but generally they are younger than

254-473: A druse (a layer of crystals lining a void), of which quartz geodes are particularly fine examples. The crystals are attached at one end to the enclosing rock, and only one termination pyramid is present. However, doubly terminated crystals do occur where they develop freely without attachment, for instance, within gypsum . α-quartz crystallizes in the trigonal crystal system, space group P 3 1 21 or P 3 2 21 (space group 152 or 154 resp.) depending on

381-589: A marine climate ( Cfb ). This results in larger seasonal differences than typical of marine climates in spite of it being surrounded by the Baltic Sea for large distances in all directions. This is due to strong continental winds travelling over the sea from surrounding great landmasses. Seasonal temperature variation is smaller in more isolated places on the island such as Hoburgen or Östergarnsholm, having warmer autumn and winter, but are cooler during spring and summer days. Seasonal lag being exceptionally strong in

508-560: A pressure cooker . However, the quality and size of the crystals that were produced by these early efforts were poor. Elemental impurity incorporation strongly influences the ability to process and utilize quartz. Naturally occurring quartz crystals of extremely high purity, necessary for the crucibles and other equipment used for growing silicon wafers in the semiconductor industry, are expensive and rare. These high-purity quartz are defined as containing less than 50 ppm of impurity elements. A major mining location for high purity quartz

635-509: A "quasiplatform" group of sediments of the East European Platform not being metamorphosed enough to be part of the "protoplatform" and not being undeformed enough to be part of the "cataplatform" category. By analogy to the established Sub-Cambrian peneplain that extends across much of Fennoscandia there have been suggestions of the existence of an exhumed Subjotnian peneplain . This surface actually exists but its extent

762-663: A burial context, such as Newgrange or Carrowmore in Ireland . Quartz was also used in Prehistoric Ireland , as well as many other countries, for stone tools ; both vein quartz and rock crystal were knapped as part of the lithic technology of the prehistoric peoples. While jade has been since earliest times the most prized semi-precious stone for carving in East Asia and Pre-Columbian America, in Europe and

889-487: A defining constituent of granite and other felsic igneous rocks . It is very common in sedimentary rocks such as sandstone and shale . It is a common constituent of schist , gneiss , quartzite and other metamorphic rocks . Quartz has the lowest potential for weathering in the Goldich dissolution series and consequently it is very common as a residual mineral in stream sediments and residual soils . Generally

1016-553: A farmer from Gökhem parish in Västergötland on the mainland was found to be more closely related to modern-day Mediterraneans. This is consistent with the spread of agricultural peoples from the Middle East at about that time. Gutasaga contains legends of how the island was settled by Þieluar and populated by his descendants. It also tells that a third of the population had to emigrate and settle in southern Europe,

1143-584: A high presence of quartz suggests a " mature " rock, since it indicates the rock has been heavily reworked and quartz was the primary mineral that endured heavy weathering. While the majority of quartz crystallizes from molten magma , quartz also chemically precipitates from hot hydrothermal veins as gangue , sometimes with ore minerals like gold, silver and copper. Large crystals of quartz are found in magmatic pegmatites . Well-formed crystals may reach several meters in length and weigh hundreds of kilograms. The largest documented single crystal of quartz

1270-628: A lot more attention military-wise and has seen a much larger spending on the military. As of 2018, the Gotland Regiment has been re-raised and is the first time since World War II that a new regiment has been established in Sweden. The first modern day tourists came to Gotland during the 19th century and were known as "bathers". Gotland became very popular with socialites at the time through Princess Eugenie who lived in Västerhejde , in

1397-703: A military standpoint, it occupies a strategic location at the center of the Baltic Sea . The name of Gotland is closely related to that of the Geats and Goths . The island was the home of the Gutes , and sites such as the Ajvide Settlement show that it has been occupied since prehistory . A DNA study conducted on the 5,000-year-old skeletal remains of three Middle Neolithic seal hunters from Gotland showed that they were related to modern-day Finns , while

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1524-531: A naval base in the past, as of 2004 , there are no naval units based on Gotland. The Tofta firing range itself (also known as the Tofta Tank firing range), is a military training ground which is located 8 km (5.0 mi) south of Visby. Another less common name for the range is the Toftasjön firing range. Tracing its origins back to 1898, as of 2008 the range extended over 2,700 acres (11 km ). It

1651-536: A number of these grinding grooves to the Stone Age, from c.  3300 BC to c.  2000 BC , based on astronomical alignments, although his methodology has been heavily criticized. The Medieval town of Visby has been entered as a site of the UNESCO World heritage programme. An impressive feature of Visby is the fortress wall that surrounds the old city, dating from the 13th century. Many of

1778-465: A permanent fixed link to the main island. Residents are depending on an around the clock, free of charge, car ferry for transportation over a strait roughly 1.3 km (0.81 mi) wide, taking about eight minutes. Fårö may get connected to the main island with a bridge in the future, but the project has had plenty of delays related to funding. At the closest point, the two islands are separated by less than 500 metres (1,600 ft), although that

1905-487: A ram statant Argent armed Or holding on a cross-staff of the same a banner Gules bordered and with five tails of the third." The county was granted the same coat of arms in 1936. The municipality, created in 1971, uses the same picture, but with other tinctures . Gotland is Sweden's largest island, and it is the largest island fully encompassed by the Baltic Sea (with Denmark's Zealand at the Baltic's edge). With its total area of 3,183.7 km (1,229.2 sq mi)

2032-582: A reserve component of the Swedish Amphibious Corps . Among the residual war reserve stocks reported to be still in storage on Gotland in March 2015, were 14 tanks ( Stridsvagn 122s ) at the Tofta skjutfält (the Tofta firing range), but without any crews or dedicated maintenance personnel assigned to them. Gotland currently has no local air defence capability. Despite its importance as

2159-517: A rich heritage of folklore, including myths about the bysen , Di sma undar jordi , Hoburgsgubben and the Martebo lights . Gotland gives its name to the traditional farmhouse ale Gotlandsdricka , a turbid beer with much in common with Finnish sahti , and related beers from the Baltic states . There are a number of notable people born or living on Gotland, or in other major ways associated with

2286-574: A small Brazilian mine, but it is also seen in Lower Silesia in Poland . Naturally occurring prasiolite is also found in the Thunder Bay area of Canada . Quartz crystals have piezoelectric properties; they develop an electric potential upon the application of mechanical stress . Quartz's piezoelectric properties were discovered by Jacques and Pierre Curie in 1880. Quartz is

2413-405: A small strip of these sediments running north from the main area. The Almesåkra Group extends over an area of about 380 km (150 sq mi). The Almesåkra Group consists of feldspar -rich sandstones, argillites and minor amounts of conglomerate. The deposits are believed to be of fluvial origin. Argillites constitute about 10% of the outcrops while the sandstones and conglomerates make up

2540-437: A submicroscopic distribution of colloidal ferric hydroxide impurities. Natural citrines are rare; most commercial citrines are heat-treated amethysts or smoky quartzes . However, a heat-treated amethyst will have small lines in the crystal, as opposed to a natural citrine's cloudy or smoky appearance. It is nearly impossible to differentiate between cut citrine and yellow topaz visually, but they differ in hardness . Brazil

2667-680: A superstition that it would bring prosperity. Citrine was first appreciated as a golden-yellow gemstone in Greece between 300 and 150 BC, during the Hellenistic Age . Yellow quartz was used prior to that to decorate jewelry and tools but it was not highly sought after. Milk quartz or milky quartz is the most common variety of crystalline quartz. The white color is caused by minute fluid inclusions of gas, liquid, or both, trapped during crystal formation, making it of little value for optical and quality gemstone applications. Rose quartz

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2794-576: A tradition associated with the migration of the Goths , whose name has the same origin as Gutes , the native name of the people of the island. It later tells that the Gutes voluntarily submitted to the king of Sweden and asserts that the submission was based on mutual agreement, and notes the duties and obligations of the Swedish King and Bishop in relationship to Gotland. According to some historians, it

2921-477: A year. In 2007, the number of passengers exceeded 1.5 million. In 2012, the ferries had 1,590,271 passengers and the airlines 327,255 passengers. Even during the COVID-19 pandemic tourism did not change much as Swedes chose to visit the island instead of travelling abroad. The main port of call on Gotland is Visby. The city is visited by a number of cruise ships every year. About 40 cruise lines frequent

3048-442: Is Lojsta Hed which stands 82 m (269 ft) above sea level. The average height of the island is 29 meters. Settlements besides Visby include: Of these, Hemse is the largest settlement in southern Gotland and along with Roma the two largest inland villages. Burgsvik is the southernmost locality and Fårösund the northernmost. The island of Fårö is permanently settled, but with only a few hundred year-round residents and lacks

3175-542: Is a form of quartz that ranges from a bright vivid violet to a dark or dull lavender shade. The world's largest deposits of amethysts can be found in Brazil, Mexico, Uruguay, Russia, France, Namibia, and Morocco. Sometimes amethyst and citrine are found growing in the same crystal. It is then referred to as ametrine . Amethyst derives its color from traces of iron in its structure. Blue quartz contains inclusions of fibrous magnesio-riebeckite or crocidolite . Inclusions of

3302-419: Is a monoclinic polymorph. Lechatelierite is an amorphous silica glass SiO 2 which is formed by lightning strikes in quartz sand . As quartz is a form of silica, it is a possible cause for concern in various workplaces. Cutting, grinding, chipping, sanding, drilling, and polishing natural and manufactured stone products can release hazardous levels of very small, crystalline silica dust particles into

3429-463: Is a primary identifier for the macrocrystalline varieties. Pure quartz, traditionally called rock crystal or clear quartz, is colorless and transparent or translucent and has often been used for hardstone carvings , such as the Lothair Crystal . Common colored varieties include citrine, rose quartz, amethyst, smoky quartz, milky quartz, and others. These color differentiations arise from

3556-530: Is a site of Jotnian sediment occurrence. At this location Jotnian sediments can be found within the Muhos Graben that has had a downward displacement of about one kilometre. The sediments in the Muhos Graben at the bottom are conglomerates and arkoses whose contact with the underlying metamorphic rocks constitute an unconformity . The pebbles of the conglomerate are made of schist and granite while

3683-400: Is a type of quartz that exhibits a pale pink to rose red hue. The color is usually considered as due to trace amounts of titanium , iron , or manganese in the material. Some rose quartz contains microscopic rutile needles that produce asterism in transmitted light. Recent X-ray diffraction studies suggest that the color is due to thin microscopic fibers of possibly dumortierite within

3810-521: Is also a province / county (Swedish län), municipality , and diocese . The province includes the islands of Fårö and Gotska Sandön to the north, as well as the Karlsö Islands ( Lilla and Stora ) to the west. The population is 61,023 (2024) of which about 23,600 live in Visby , the main town. Outside Visby, there are minor settlements and a mainly rural population. The island of Gotland and

3937-604: Is also possible that some beds were deposited in tidal flats or as aeolianites . Similarly to the Gävle sandstones, the outcrops at Nordingrå are linked to the Satakunta outcrops in Finland. The sediments are both intruded and covered by diabase . In the island of Tärnö Jotnian sandstone xenoliths have been found in a diabase dyke . These xenoliths have been interpreted as originating from Jotnian cover rocks lying above

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4064-402: Is at a distance from road connections. Slite is the largest settlement on Gotland's sparsely populated east coast. The eastern coast of Gotland, including the adjacent marine waters and islets, has been designated an 150,000 ha Important Bird Area (IBA) by BirdLife International because it supports a suite of waterfowl , waders and terns . Gotland has a semi-continental variety of

4191-600: Is at least 600 metres thick but might likely be as thick as much as 1800 metres. 1270–1250 million years old Postjotnian olivine -bearing diabase dykes cuts through the Satakunta Sandstones. Sedimentary and volcanic rocks crop out on the eastern shores of the Lake Ladoga in Russia. Among these are the "Salmi series" or "Salma suite" and the "Priosersk suite", which are Jotnian units. These rocks overlie

4318-623: Is known as Subjotnian rocks which include weathered rapakivi granites and the Hogland Series . Amantov and co-workers comments about the terms Jotnian and Postjotnian that: the terms should be interpreted as more descriptive (i.e. the diabase usually cuts the sandstone) than temporal (all the Jotnian sandstones not necessarily older than all the Postjotnian diabases). At large scale, Jotnian sediments are classified as being part of

4445-654: Is known as the "Trysil sandstone". At Idre drilling has revealed that the Dala sandstone extends beneath the Caledonian nappes . The Dala sandstone unconformably overlies the Transscandinavian Igneous Belt basement. The unconformity, believed to have been formed by subaerial erosion, was the surface of a peneplain at the time of deposition of the Dala sandstone. The peneplain landscape formed after protracted periods of erosion. Sedimentation of

4572-523: Is often twinned , synthetic quartz is produced for use in industry. Large, flawless, single crystals are synthesized in an autoclave via the hydrothermal process . Like other crystals, quartz may be coated with metal vapors to give it an attractive sheen. Quartz is the most common material identified as the mystical substance maban in Australian Aboriginal mythology . It is found regularly in passage tomb cemeteries in Europe in

4699-469: Is possible that the Dala sandstone was once connected to the Gulf of Bothnia by an epicontinental sea . The Dala sandstone constitute a part of broad north-south aligned syncline . Sedimentation at Dalarna happened apparently not in a graben or rift as is the case for most other Jotnian sediments. Onshore Jotnian sediments at Gävle (Gävle sandstone) have an estimated maximum thickness of 900 metres. Along with

4826-729: Is the Spruce Pine Gem Mine in Spruce Pine, North Carolina , United States. Quartz may also be found in Caldoveiro Peak , in Asturias , Spain. By the 1930s, the electronics industry had become dependent on quartz crystals. The only source of suitable crystals was Brazil; however, World War II disrupted the supplies from Brazil, so nations attempted to synthesize quartz on a commercial scale. German mineralogist Richard Nacken (1884–1971) achieved some success during

4953-475: Is the leading producer of citrine, with much of its production coming from the state of Rio Grande do Sul . The name is derived from the Latin word citrina which means "yellow" and is also the origin of the word " citron ". Sometimes citrine and amethyst can be found together in the same crystal, which is then referred to as ametrine . Citrine has been referred to as the "merchant's stone" or "money stone", due to

5080-685: Is the second most abundant mineral in Earth 's continental crust , behind feldspar . Quartz exists in two forms, the normal α-quartz and the high-temperature β-quartz, both of which are chiral . The transformation from α-quartz to β-quartz takes place abruptly at 573 °C (846 K; 1,063 °F). Since the transformation is accompanied by a significant change in volume, it can easily induce microfracturing of ceramics or rocks passing through this temperature threshold. There are many different varieties of quartz, several of which are classified as gemstones . Since antiquity, varieties of quartz have been

5207-471: Is therefore an effort not only to write down the history of Gotland, but also to assert Gotland's independence from Sweden. It gives Awair Strabain as the name of the man who arranged the mutually beneficial agreement with the king of Sweden; the event would have taken place before the end of the ninth century, when Wulfstan of Hedeby reported that the island was subject to the Swedes: Then, after

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5334-412: Is used for very accurate measurements of very small mass changes in the quartz crystal microbalance and in thin-film thickness monitors . Almost all the industrial demand for quartz crystal (used primarily in electronics) is met with synthetic quartz produced by the hydrothermal process. However, synthetic crystals are less prized for use as gemstones. The popularity of crystal healing has increased

5461-493: Is very limited, represented as small valley plains at Sveg and along the Västerdalälven - Dalälven system. There is evidence suggesting that Jotnian cover rocks or a Jotnian platform once covered much of Fennoscandia and were not restricted to a few localities like today. The limited geographical extent of Jotnian sediments at present is indebted to their erosion over geological time . Sedimentary rocks as old as

5588-519: The Baltic Syneclise . Quartz Quartz is a hard, crystalline mineral composed of silica ( silicon dioxide ). The atoms are linked in a continuous framework of SiO 4 silicon–oxygen tetrahedra , with each oxygen being shared between two tetrahedra, giving an overall chemical formula of SiO 2 . Quartz is, therefore, classified structurally as a framework silicate mineral and compositionally as an oxide mineral . Quartz

5715-643: The Carolingian Empire , as major commercial centers for the next several centuries. The Berezan' Runestone , discovered in 1905 in Ukraine, was made by a Varangian ( Viking ) trader named Grani in memory of his business partner Karl. It is assumed that they were from Gotland. The Mästermyr chest , an important artefact from the Viking Age , was found in Gotland. On 16   July 1999,

5842-459: The Finnish War between Sweden and Russia, a Russian army landed on the southeastern shores of Gotland near Grötlingbo . Under command of Nikolai Andreevich Bodisko 1,800 Russians took the city of Visby without any combat or engagement, and occupied the island. A Swedish naval force rescue expedition was sent from Karlskrona under the command of admiral Rudolf Cederström with 2,000 men;

5969-718: The Gulf of Bothnia , the Bothnian Sea and the Åland Sea including South Kvarken . Known Jotnian rocks at the Åland Sea are sandstones and belong to the Söderarm Formation (informal). Above these there are Upper riphean and Vendian sandstones and shales. Fully within Swedish waters there is a Jotnian sediment occurrence at the Landsort Basin between Gotland and Stockholm archipelago . Jotnian rocks found in

6096-531: The Tersky Coast at the southern shores of the Kola Peninsula . These outcrops are an overfill of the neighbouring Kandalaksha Graben , which is also filled with these sediments. The formation has silty beds within a matrix of mica and clay . The Tersky Formation was deposited in the timespan between 1263 and 1080 million years ago (±40 million years of error). The neighboring Kerets Graben in

6223-667: The Teutonic Knights , awarded to them on the condition that they expel the piratical Victual Brothers from their fortified sanctuary . An invading army of Teutonic Knights conquered the island in 1398, destroying Visby and driving the Victual Brothers from Gotland. In 1409, Grand Master Ulrich von Jungingen of the Teutonic Knights guaranteed peace with the Kalmar Union of Scandinavia by selling

6350-524: The hexagonal crystal system above 573 °C (846 K; 1,063 °F). The ideal crystal shape is a six-sided prism terminating with six-sided pyramid-like rhombohedrons at each end. In nature, quartz crystals are often twinned (with twin right-handed and left-handed quartz crystals), distorted, or so intergrown with adjacent crystals of quartz or other minerals as to only show part of this shape, or to lack obvious crystal faces altogether and appear massive . Well-formed crystals typically form as

6477-525: The land of the Burgundians , we had on our left the lands that have been called from the earliest times Blekingey , and Meore , and Eowland , and Gotland, all which territory is subject to the Sweons ; and Weonodland was all the way on our right, as far as Weissel -mouth. The number of Arab dirhams discovered on the island of Gotland alone is astoundingly high. In the various hoards located around

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6604-417: The matrix is made of arkose. The bulk (90–80%) of the sequence of sediments is made up of siltstones and shales . The colour of the siltstones and shales vary from red and brown to grey to green. The siltstones and shales are intercalated with arkosic sandstone. The red arkosic sandstones of Muhos Graben are comparable to the ones of Satakunta. These sediments are of fluvial origin. Southern Satakunta near

6731-624: The sunny climate and the extensive shoreline bordering mild waters. During summer, Visby hosts the political event Almedalen Week , followed by the Medieval Week , further boosting visitor numbers. In winter, Gotland usually remains surrounded by ice-free water and has mild weather. Gotland has been inhabited since approximately 7200 BC. The island's main sources of income are agriculture, food processing, tourism, information technology services, design, and some heavy industry such as concrete production from locally mined limestone . From

6858-553: The "Pasha–Ladoga structure", which is also in part a syncline, thus being referred to as graben-syncline. The maximum thickness of the pile of sediments is no less than 800 metres. Jotnian sediments are exposed only as small outcrops on land but exposures are larger at the lake bottom. The Rybachy Peninsula in northern Murmansk Oblast hosts Jotnian sedimentary rocks dated to have sedimented 1126±50 million years ago. These rocks are thrusted over by younger Vendian and Upper Riphean rocks. The Jotnian Tersky Formation crops out along

6985-879: The 14th century in Middle High German and in East Central German and which came from the Polish dialect term twardy , which corresponds to the Czech term tvrdý ("hard"). Some sources, however, attribute the word's origin to the Saxon word Querkluftertz , meaning cross-vein ore . The Ancient Greeks referred to quartz as κρύσταλλος ( krustallos ) derived from the Ancient Greek κρύος ( kruos ) meaning "icy cold", because some philosophers (including Theophrastus ) understood

7112-620: The 1930s and 1940s. After the war, many laboratories attempted to grow large quartz crystals. In the United States, the U.S. Army Signal Corps contracted with Bell Laboratories and with the Brush Development Company of Cleveland, Ohio to synthesize crystals following Nacken's lead. (Prior to World War II, Brush Development produced piezoelectric crystals for record players.) By 1948, Brush Development had grown crystals that were 1.5 inches (3.8 cm) in diameter,

7239-536: The Almesåkra Group as originating from first phases of erosion of the uplifted Sveconorwegian region to the west. Near Brevik in Eksjö Municipality and Röjda  [ sv ] , there are diabase dykes hosting numerous rounded clasts of red Jotnian sandstone including both quartz arenite and arkose . These Jotnian xenoliths are interpreted as having been part of a conglomerate that

7366-442: The Baltic sea with Visby as one of their destinations. In 2005, 147 ships docked at Visby, in 2010 the number was 69. In 2014, 62 ships are scheduled to visit Visby. The decrease in visiting ships is due to the fact that the modern cruise ships are too large to enter Visby harbor. Ships must anchor a fair distance from shore whereupon passengers are shuttled to shore in small boats, which is not possible during bad weather. In 2007,

7493-408: The Dala sandstone happened between 1650 and 1200 million years ago. The maximum thickness of the sediments at Dalarna is 800 m. The lowermost sediments are conglomerates and breccias . Above this basal layer, sediments are mainly stratified red sandstone intercalated with shale and conglomerate. Among the sandstones there are greywacke sandstones and quartz-rich sandstones. A remarkable feature on

7620-711: The Dala sandstone the Gävle sandstone has been subject to low grade burial metamorphism of the pumpellyite type, meaning they must once have been buried beneath several kilometres of sediments. Together with the Jotnian sediments of Nordingrå the Gävle sandstone share links with the Satakunta Jotnian rocks. Archaeological finds show that Gävle sandstone has been used as millstone in Lejstaån near Uppsala . Jotnian sandstone crops out around Södra Björkfjärden in Lake Mälaren . Visible outcrops can be found in

7747-477: The Dala sandstones is that delicate features like ripple marks , rain drop marks and mudcracks have survived in the sediments. The sandstones in Dalarna are of aeolian origin and represent ancient dunes and interdune sediments. The Dala sandstone has an imprint of low grade burial metamorphism of the pumpellyite type , meaning they must once have been buried beneath several kilometres of sediments. It

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7874-457: The Earth's crust exposed to high temperatures, thereby damaging materials containing quartz and degrading their physical and mechanical properties. Although many of the varietal names historically arose from the color of the mineral, current scientific naming schemes refer primarily to the microstructure of the mineral. Color is a secondary identifier for the cryptocrystalline minerals, although it

8001-547: The Jotnian sediments age have a low preservation potential . The distribution of some Jotnian sediments is spatially associated with the occurrence of rapakivi granite. Korja and co-workers (1993) claim the Jotnian sediment–rapakivi granite coincidence at the Gulf of Finland and the Gulf of Bothnia is associated with the existence of thin crust at these locations. At present Jotnian sedimentary rocks are commonly found in half-grabens , narrow grabens , in slightly downfolded (syncline) positions or in mixed graben-synclines. Most of

8128-670: The Landsort Basin are red sandstones. In the Bothnian Sea offshore Pori in Satakunta Jotnian sediments reaches a thickness of thousand metres, in other locations thickness is much less, for example 100 m at the Sylen shoal and yet in other places of the Bothnian Sea Jotnian sediments are absent. The Sub-Cambrian peneplain cuts across Jotnian rocks in the Bothnian Sea. Muhos in the northeastern Gulf of Bothnia

8255-406: The Middle East the different varieties of quartz were the most commonly used for the various types of jewelry and hardstone carving , including engraved gems and cameo gems , rock crystal vases , and extravagant vessels. The tradition continued to produce objects that were very highly valued until the mid-19th century, when it largely fell from fashion except in jewelry. Cameo technique exploits

8382-419: The Midsummer's Eve celebration on the island, but also throughout the summer months. The games have widespread renown; some of them are played by people as far away as in the United States. The knotwork design subsequently named the " Valknut " has the most attested historic instances on picture stones in Gotland, which include being on both the Stora Hammars I and the Tängelgårda stones . Gotland also has

8509-449: The Nordingrå area display often cross-bedding and ripple marks . There are also fossil dunes . At Ringkallen the pile of Jotnian sediments is of 65 metres. Exposed sediment profiles show considerable variation in sedimentary facies . The deposition environment for sandstones including the arkose was one of an embankment or a channel with little current. The environment was likely one of a river as paleocurrents are somewhat uniform. It

8636-431: The Romanesque style from 1150 to 1250. The newer churches were constructed in the Gothic architectural style that prevailed from about 1250–1400. The oldest painting inside one of the churches on Gotland stretches as far back in time as the 12th century. Traditional games of skill like Kubb , Pärk , and Varpa are played on Gotland. They are part of what has become called "Gutniska Lekar", and are performed preferably on

8763-406: The Salma rapakivi granite and igneous and metamorphic rocks of Paleoproterozoic age. Gritstone , sandstone and conglomerate are the sedimentary components of the Salmi suite which further includes mafic volcanic rocks . As with Satakunta and Muhos in Finland, the sediments at Lake Ladoga are located in a graben of Late Proterozoic age. The graben structure that hosts the sediments is known as

8890-400: The White Sea is filled with 2000–1500 metres of Jotnian sediments. In Sweden Jotnian rocks can be found in Dalarna , Gävle , Nordingrå , Svartälven  [ sv ] , Lake Mälaren and Almesåkra  [ sv ] (Almesåkra Group). The Jotnian Almesåkra Group of sediments lie in northern Småland in a triangle-shaped area centered around Nässjö , in addition to this there is

9017-441: The air that workers breathe. Crystalline silica of respirable size is a recognized human carcinogen and may lead to other diseases of the lungs such as silicosis and pulmonary fibrosis . Not all varieties of quartz are naturally occurring. Some clear quartz crystals can be treated using heat or gamma-irradiation to induce color where it would not otherwise have occurred naturally. Susceptibility to such treatments depends on

9144-407: The bands of color in onyx and other varieties. Efforts to synthesize quartz began in the mid-nineteenth century as scientists attempted to create minerals under laboratory conditions that mimicked the conditions in which the minerals formed in nature: German geologist Karl Emil von Schafhäutl (1803–1890) was the first person to synthesize quartz when in 1845 he created microscopic quartz crystals in

9271-632: The basement below the sediments is made of granites and pegmatites of the Svecofennian orogeny . In the Nordingrå area, spanning from Malmön to Hernön , Jotnian sediments rest on a complex of gabbros , monzogranite , granites and anorthosites . Jotnian sediments consist of quartz-rich sandstone , arkose and conglomerate . The sandstone and arkose have black and violet coloured siltstone and shale lenses and beds. Siltstone beds are commonly 5 to 10 centimetres thick. Jotnian sediments in

9398-515: The buildings on the range, the former tank repair shop , is currently owned by a private company ( Peab ), with the military renting back the top floor for its own use. When not used by the military, a number of cultural and sports events have been held at the range, one of the most notable being the Gotland Grand National  [ sv ] , the world's largest enduro race, from 1984 to 2023. As of 2018, Gotland has received

9525-410: The bulk of this initial garrison will make up a new motorised rifle battalion, alternatively referred to in other reports as a "modular-structured rapid response Army battalion". A later report claimed that plans were at an advanced stage for a support helicopter squadron and an Air Force "fast response Gripen jet squadron" to also be based on the island to support the new garrison and further reinforce

9652-444: The chirality. Above 573 °C (846 K; 1,063 °F), α-quartz in P 3 1 21 becomes the more symmetric hexagonal P 6 4 22 (space group 181), and α-quartz in P 3 2 21 goes to space group P 6 2 22 (no. 180). These space groups are truly chiral (they each belong to the 11 enantiomorphous pairs). Both α-quartz and β-quartz are examples of chiral crystal structures composed of achiral building blocks (SiO 4 tetrahedra in

9779-556: The countryside had to be put down by King Magnus III of Sweden in 1288. In 1361, Valdemar Atterdag of Denmark invaded the island. About 1,500 Gotlandic farmers were killed by the Danish invaders after massing for the Battle of Mästerby . The Victual Brothers occupied the island in 1394 to set up a stronghold as a headquarters of their own in Visby. At last, Gotland became a fief of

9906-466: The crystal structure. Prase is a green variety of quartz. The green color is caused by inclusions of amphibole . Prasiolite , also known as vermarine , is a variety of quartz that is green in color. The green is caused by iron ions. It is a rare mineral in nature and is typically found with amethyst; most "prasiolite" is not natural – it has been artificially produced by heating of amethyst. Since 1950 , almost all natural prasiolite has come from

10033-433: The crystals. Tridymite and cristobalite are high-temperature polymorphs of SiO 2 that occur in high-silica volcanic rocks. Coesite is a denser polymorph of SiO 2 found in some meteorite impact sites and in metamorphic rocks formed at pressures greater than those typical of the Earth's crust. Stishovite is a yet denser and higher-pressure polymorph of SiO 2 found in some meteorite impact sites. Moganite

10160-572: The defences. Prior to the disbandment of the original garrison, there had been a continuous Swedish military presence on Gotland in one form or another, for nearly 200 years. After the standing down of the original garrison, a battalion of the Swedish Home Guard is based on Gotland for emergencies as part of the Eastern Military Region ( MR E ). The unit, 32:a Gotlandsbataljonen (the 32nd Gotland battalion), acts as

10287-477: The demand for natural quartz crystals, which are now often mined in developing countries using primitive mining methods, sometimes involving child labor . Gotland Gotland ( / ˈ ɡ ɒ t l ə n d / , Swedish: [ˈɡɔ̌tːland] ; Gutland in Gutnish ), also historically spelled Gottland or Gothland ( / ˈ ɡ ɒ θ l ə n d / ), is Sweden's largest island. It

10414-541: The dyke that have since been eroded. Once the dyke intruded, Jotnian rock fragments would have been incorporated into the dyke and then went down during a "reversal of magma ascent". The relationships of the dyke with Jotnian sediments suggest that magma intruded wet sediments as a sort of peperite . Jotnian sediments (mostly quartz sandstone and siltstone) exist at some locations beneath the Phanerozoic platform sediments of western Latvia and western Lithuania within

10541-454: The finding of glauconite in the Jotnian rocks of the northwestern part of the outcrop , it has been suggested that at least in that place the diagenesis occurred under water. It is found in a northwest-southeast trending graben structure that has helped to preserve the sediments. This graben has seen a downward displacement of about 650 metres. The Satakunta sandstone is not younger than 1400–1300 million years. The Satakunta sedimentary pile

10668-453: The first proposition for building a new pier at Visby harbor, large enough to serve the modern cruise ships, was made. In 2011, the matter of the new pier was discussed in the Riksdag and in 2012 research and planning for the pier began. In January 2014, a letter of intent for building a new cruise pier in Visby harbor was signed by Region Gotland and Copenhagen Malmö Port (CMP). The pier

10795-623: The grabens hosting Jotnian sediments are northwest-southeast oriented. The largest occurrence of Jotnian sediments appear however to occur neither in a rift or a graben and lie in Dalarna , Sweden. It has been suggested that the sedimentary basins hosting Jotnian sediments at Dalarna, Gävle , the Bothnian Sea , Satakunta and Lake Ladoga form an alignment of subsidence parallel to the area of inferred Hallandian-Danopolonian subduction , possibly corresponding to an ancient back-arc basin . Between Finland and Sweden Jotnian sediments are common in

10922-442: The hands. This idea persisted until at least the 17th century. He also knew of the ability of quartz to split light into a spectrum . In the 17th century, Nicolas Steno 's study of quartz paved the way for modern crystallography . He discovered that regardless of a quartz crystal's size or shape, its long prism faces always joined at a perfect 60° angle. Quartz belongs to the trigonal crystal system at room temperature, and to

11049-437: The impurities of phosphate and aluminium that formed crystalline rose quartz, unlike the iron and microscopic dumortierite fibers that formed rose quartz. Smoky quartz is a gray, translucent version of quartz. It ranges in clarity from almost complete transparency to a brownish-gray crystal that is almost opaque. Some can also be black. The translucency results from natural irradiation acting on minute traces of aluminum in

11176-465: The island had twenty district courts ( tings ), each represented by its elected judge at the island-ting, called landsting . New laws were decided at the landsting, which also took other decisions regarding the island as a whole. The city of Visby and rest of the island were governed separately, and a civil war caused by conflicts between the German merchants in Visby and the peasants they traded with in

11303-691: The island has remained under Swedish rule. On 19 September 1806, Gustav IV Adolf offered the sovereignty of Gotland to the Order of St. John of Jerusalem , who had been expelled from Malta in 1798, but the Order rejected the offer since it would have meant renouncing their claim to Malta. The Order never regained its territory, and eventually it reestablished itself in Rome as the Sovereign Military Order of Malta . On 22 April 1808, during

11430-480: The island of Gotland and the other areas of the province of Gotland make up 0.8% of Sweden's total land area. The province includes the small islands of Fårö and Gotska Sandön to the north, as well as the Karlsö Islands, (Lilla and Stora) to the west, which are even smaller. The island of Gotland has an area of 2,994 km (1,156 sq mi), whereas the province has 3,183.7 km (1,229.2 sq mi) [3,151 km (1,217 sq mi) of land excluding

11557-532: The island of Gotland to Queen Margaret of Denmark, Norway and Sweden . The authority of the landsting was successively eroded after the island was occupied by the Teutonic Order, then sold to Eric of Pomerania and after 1449 ruled by Danish governors. In late medieval times, the ting consisted of twelve representatives for the farmers, free-holders or tenants. Since the Treaty of Brömsebro in 1645,

11684-473: The island was liberated and the Russians capitulated. Russian forces left the island on 18 May 1808. The traditional provinces of Sweden serve no administrative or political purposes today, but are historical and cultural entities. In the case of Gotland, however, due to its insular position, the administrative county ( län ), Gotland County , and the municipality ( kommun ), Region Gotland , both cover

11811-614: The island, there are more of these silver coins than at any other site in Western Eurasia. The total sum is almost as great as the number that has been unearthed in the entire Muslim world. These coins moved north through trade between Rus merchants and the Abbasid Caliphate , along the Silver-Fur Road , and the money made by Scandinavian merchants would help northern Europe, especially Viking Scandinavia and

11938-436: The island; palæo- sea-stacks are preserved in places. The island's main sources of income are agriculture along with food processing, tourism, IT solutions, design and some heavy industry such as concrete production from locally mined limestone . Most of Gotland's economy is based on small scale production. In 2012, there were over 7,500 registered companies on Gotland. 1,500 of these had more than one employee. Gotland has

12065-401: The lakes and rivers]. The population is 61,001 as of December 2021. As of 2016, approximately 23,600 people (about 40% of residents) lived in Visby, which is the seat of the municipality and the capital of the county. Gotland is located about 90 km (56 mi) east of the Swedish mainland and about 130 km (81 mi) from the Baltic states , Latvia being the nearest. Gotland is

12192-452: The largest at that time. By the 1950s, hydrothermal synthesis techniques were producing synthetic quartz crystals on an industrial scale, and today virtually all the quartz crystal used in the modern electronics industry is synthetic. An early use of the piezoelectricity of quartz crystals was in phonograph pickups. One of the most common piezoelectric uses of quartz today is as a crystal oscillator . The quartz oscillator or resonator

12319-550: The locality of Rasta in western Ekerön island and several small islands and islets: Midsommar, Pingst, Gåsholmen, Gåsholmsskäret and Gåsholmshatten, the last three being part of a nature reserve. Jotnian sandstone also occurs at the bottom of Björkjärden and studies of glacial erratics suggest there is unexposed Jotnian sandstone to north of the Björkfjärden area, where the outcrops are vestiges of an eroded Precambrian meteorite crater , filled with Jotnian sediments. At Rasta,

12446-517: The location from which the quartz was mined. Prasiolite, an olive colored material, is produced by heat treatment; natural prasiolite has also been observed in Lower Silesia in Poland. Although citrine occurs naturally, the majority is the result of heat-treating amethyst or smoky quartz. Carnelian has been heat-treated to deepen its color since prehistoric times. Because natural quartz

12573-421: The mineral dumortierite within quartz pieces often result in silky-appearing splotches with a blue hue. Shades of purple or gray sometimes also are present. "Dumortierite quartz" (sometimes called "blue quartz") will sometimes feature contrasting light and dark color zones across the material. "Blue quartz" is a minor gemstone. Citrine is a variety of quartz whose color ranges from pale yellow to brown due to

12700-571: The mineral to be a form of supercooled ice. Today, the term rock crystal is sometimes used as an alternative name for transparent coarsely crystalline quartz. Roman naturalist Pliny the Elder believed quartz to be water ice , permanently frozen after great lengths of time. He supported this idea by saying that quartz is found near glaciers in the Alps, but not on volcanic mountains, and that large quartz crystals were fashioned into spheres to cool

12827-501: The most commonly used minerals in the making of jewelry and hardstone carvings , especially in Europe and Asia. Quartz is the mineral defining the value of 7 on the Mohs scale of hardness , a qualitative scratch method for determining the hardness of a material to abrasion. The word "quartz" is derived from the German word Quarz , which had the same form in the first half of

12954-456: The name of the main island, but the adjacent islands are generally considered part of Gotland and the Gotlandic culture: There are several shallow lakes located near the shores of the island. The biggest is Lake Bästeträsk , located near Fleringe in the northern part of Gotland. The Hoburg Shoal bird reserve is situated on the southern tip of the island. The highest point of the island

13081-529: The other areas of the province of Gotland make up less than one percent of Sweden's total land area. The county formed by the archipelago is the second smallest by area and is the least populated in Sweden. In spite of the small size due to its narrow width, the driving distance between the furthermost points of the populated islands is about 170 kilometres (110 mi). Gotland is a fully integrated part of Sweden with no particular autonomy, unlike several other offshore island groups in Europe. Historically, there

13208-494: The presence of impurities which change the molecular orbitals, causing some electronic transitions to take place in the visible spectrum causing colors. The most important distinction between types of quartz is that of macrocrystalline (individual crystals visible to the unaided eye) and the microcrystalline or cryptocrystalline varieties ( aggregates of crystals visible only under high magnification). The cryptocrystalline varieties are either translucent or mostly opaque, while

13335-403: The present case). The transformation between α- and β-quartz only involves a comparatively minor rotation of the tetrahedra with respect to one another, without a change in the way they are linked. However, there is a significant change in volume during this transition, and this can result in significant microfracturing in ceramics during firing, in ornamental stone after a fire and in rocks of

13462-510: The quartz. Additionally, there is a rare type of pink quartz (also frequently called crystalline rose quartz) with color that is thought to be caused by trace amounts of phosphate or aluminium . The color in crystals is apparently photosensitive and subject to fading. The first crystals were found in a pegmatite found near Rumford , Maine , US, and in Minas Gerais , Brazil. The crystals found are more transparent and euhedral, due to

13589-554: The rapakivi granites and older than Postjotnian diabases that intrude the sediments. This means that Jotnian sediments were deposited approximately 1600–1260 million years ago. Some Jotnian sediments are, however, younger than the diabases, meaning they can be younger than 1260 million years. Jotnian sediments are usually assigned to the Riphean Stage of the Mesoproterozoic Era . Jotnian sediments rests on what

13716-435: The remaining 90% of outcrops. The sedimentary pile is at most not more than 1200 metres thick. The Almesåkra Group is tectonically disturbed, shows considerable folding and is intruded by diabase. Almesåkra Group overlies the plutons of the Transscandinavian Igneous Belt . At least in some outcrops the lowermost sediments are arkoses, presumably of local origin as grus . Geologists Eva-Lena Tullborg and co-workers consider

13843-696: The residents still speak Gutnish (Gutamål), the autochthonous language on the islands. But most of them now speak Gotlandic ( Swedish : gotländska ), a Gutnish-influenced Swedish dialect. In the 13th century, a work containing the laws of the island, called "the Gotlandic law" (Gutalagen), was published in Old Gutnish , as well as the Gutasaga . Gotland is noted for its 94 Medieval churches , most of which are restored and in active use. These churches exhibit two major styles of architecture: Romanesque and Gothic . The older churches were constructed in

13970-421: The same territory as the province. Furthermore, the diocese of Visby is also congruent with the province. Gotland is traditionally divided into 92 sockens . On 1   January 2016, they were all reconstituted into Districts , administrative areas with the same borders as the former sockens. Gotland was granted its arms in about 1560. The coat of arms is represented with a ducal coronet. Blazon: "Azure

14097-451: The sea was 50 to 100 m (160 to 330 ft), and reefs continued to dominate the sedimentary record. Some sandstones are present in the youngest rocks towards the south of the island, which represent sand bars deposited very close to the shoreline. The lime rocks have been weathered into characteristic karstic rock formations known as rauks . Fossils, mainly of crinoids , rugose corals and brachiopods , are abundant throughout

14224-423: The shores of the Bothnian Sea hosts some Jotnian sediments known as Satakunta sandstone. This sediments are arkosic sandstones of red colour and clear stratification that are intercalated with lesser amounts of red or black shale. According to the sediments mineralogical as well as geochemical characteristics they are classified as immature . The Satakunda sandstones is a fluvial sediment formation . Based on

14351-473: The south, and overlies a 75 to 125 m (246 to 410 ft) thick Ordovician sequence. It was deposited in a shallow, hot, and salty sea on the edge of an equatorial continent. The water depth never exceeded 175 to 200 m (574 to 656 ft), and became shallower over time as bioherm detritus and terrestrial sediments filled the basin. Reef growth started in the Llandovery Epoch , when

14478-414: The transparent varieties tend to be macrocrystalline. Chalcedony is a cryptocrystalline form of silica consisting of fine intergrowths of both quartz, and its monoclinic polymorph moganite . Other opaque gemstone varieties of quartz, or mixed rocks including quartz, often including contrasting bands or patterns of color, are agate , carnelian or sard, onyx , heliotrope , and jasper . Amethyst

14605-484: The weather station Östergarnsholm. As an example, December is warmer than March with temperature lows being similar to April. August is typically the warmest month, an unusual occurrence in Swedish sites. In capital Visby, July and August temperatures tend to be quite even. Since winters usually remain just above freezing and brackish water remaining liquid longer than freshwater, the sea remains ice-free all year round, except during rare extreme cold waves . The last time

14732-499: The west part of the island from the 1860s. When a new law ensuring two weeks vacation for all employees in Sweden was passed in 1938, camping became a popular pastime among the Swedes, and in 1955, Gotland was visited by 80,000 people. In the 1970s mostly young people were attracted to Gotland. Since 2010 the island has become a more versatile vacation spot visited by people from all over the world, in all manner of ways. In 2001, it

14859-490: The whole passage from the mainland to Gotland froze was in 1987 when icebreakers were used to maintain passenger and goods traffic to the island. Gotland is made up of a sequence of sedimentary rocks of a Silurian age, dipping to the south-east. The main Silurian succession of limestones and shales comprises thirteen units spanning 200 to 500 m (660 to 1,640 ft) of stratigraphic thickness, being thickest in

14986-616: The world's largest Viking silver treasure, the Spillings Hoard , was found in a field at Spillings farm northwest of Slite . The silver treasure was divided into two parts weighing a total of 67 kg (148 lb) (27 kg (60 lb) and 40 kg (88 lb)) and consisted mostly of coins, about 14,000, from foreign countries, mostly Islamic. It also contained about 20 kg (44 lb) of bronze objects along with numerous everyday objects such as nails, glass beads, parts of tools, pottery, iron bands and clasps. The treasure

15113-525: The world's northernmost established vineyard and winery, located in Hablingbo . Gotland occupies a strategic location in the Baltic sea from a defence viewpoint. In March 2015, the Swedish government decided to begin reestablishing a permanent military presence on Gotland, starting with an initial 150 troop garrison, consisting primarily of elements from the Swedish Army . It has been reported that

15240-406: Was a linguistic difference between the archipelago and the mainland with Gutnish being the native language. In recent centuries, Swedish took over almost entirely and the island is virtually monolingually Swedish in modern times. The archipelago is a very popular domestic tourist destination for mainland Swedes, with the population rising to very high numbers during summers. Some of the reasons are

15367-573: Was a major training and storage facility for the Gotland garrison during its existence, and was still occasionally used for training by various elements of the Armed Forces since the garrison was shut down in 2005. However, from the second half of 2014 onwards, there has been a marked increase in the use of the range, especially by armored units (mostly company sized), as tensions in Northeastern Europe have escalated. At least one of

15494-518: Was disintegrated by the diabase magma. The conglomerate which contained the rounded Jotnian sedimentary rock clasts has only been deduced to exist and has not found in the proximity of the diabases in question. The occurrence at Dalarna (Dala sandstone), with its 50 km x 150 km area, constitutes the largest region known to be covered at present with Jotnian sediments. The sandstone extends beyond Sweden's border into Hedmark in Norway where it

15621-749: Was finished in 2018. The estimated cost is 250 million crowns (about US$ 38.52 million). A number of stones with grooves exist on Gotland. Archaeologists interpret these grooves as traces of an unknown industrial process in the High Middle Ages . There are approximately 3,700 grinding grooves, of which about 750 occur in the solid limestone outcrop and the rest in other rock formations. The latter often consist of hard rocks such as granite or gneiss, but also soft rocks such as sandstone occur. Grinding grooves are also found in Skåne, in southern Sweden and in Finland. Astronomer Göran Henriksson dates

15748-420: Was first developed by Walter Guyton Cady in 1921. George Washington Pierce designed and patented quartz crystal oscillators in 1923. The quartz clock is a familiar device using the mineral. Warren Marrison created the first quartz oscillator clock based on the work of Cady and Pierce in 1927. The resonant frequency of a quartz crystal oscillator is changed by mechanically loading it, and this principle

15875-426: Was found by using a metal detector, and the finders fee, given to the farmer who owned the land, was over 2 million kronor (about US$ 308,000). The treasure was found almost by accident while filming a news report for TV4 about illegal treasure hunting on Gotland. Early on, Gotland became a commercial center, with the town of Visby the most important Hanseatic city in the Baltic Sea . In late medieval times,

16002-541: Was found near Itapore , Goiaz , Brazil; it measured approximately 6.1 m × 1.5 m × 1.5 m (20 ft × 5 ft × 5 ft) and weighed over 39,900 kg (88,000 lb). Quartz is extracted from open pit mines . Miners occasionally use explosives to expose deep pockets of quartz. More frequently, bulldozers and backhoes are used to remove soil and clay and expose quartz veins, which are then worked using hand tools. Care must be taken to avoid sudden temperature changes that may damage

16129-439: Was the fifth largest tourist destination in Sweden based on the total number of guest nights. Gotland is usually the part of Sweden which receives the most hours of sunlight during a year with Visby statistically the location with the most sunshine in Sweden. In 2007 approximately 750,000 people visited Gotland. In 1996, for the first time, ferries between Gotland and mainland Sweden carried more than 1 million passengers in

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