57-539: Ocnița ( Romanian pronunciation: [ ˈ o k n i ts a ] ) is a town and the administrative center of Ocnița District in northern Moldova . According to the 1930 Romanian census, the population was 96.1% Romanian , 1.7% Russian , 0.81% Jewish , 0.44% Ukrainian and 0.37% Polish . This Ocnița District location article is a stub . You can help Misplaced Pages by expanding it . Ocni%C8%9Ba District Ocnița ( Romanian pronunciation: [ ˈ o k n i ts
114-400: A ] ) is a district ( Romanian : raion ) in the north of Moldova , with the administrative center at Ocnița . The other major cities are Otaci and Frunză . As of 1 January 2011, its population was 56,100. The first evidence of a locality in the district comes from 1419, when is attested the city Otaci , called Stânca Vămii. Other historical attestations of district towns down to
171-473: 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
228-452: A framework silicate mineral and compositionally as an oxide mineral . Quartz 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
285-560: 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
342-663: 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
399-487: 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
456-584: 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
513-569: A medical point. In Health Care operates 96 doctors, 322 personal care environment, 218 and auxiliary medical personnel. 48°25′N 27°30′E / 48.417°N 27.500°E / 48.417; 27.500 Quartz sand 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
570-574: 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
627-437: 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
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#1732801481874684-680: 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
741-541: A year. Rainfall between 370 and 560mm/year, about 10% of which falls as snow, which can melt several times during winter. The fauna of the district is typical of central and eastern Europe and includes: hedgehogs , wild boars , foxes, rabbits, badgers , polecats , and rarely deer , spotted deer , wolves , and raccoon dogs . Forests occupy 13.7% of district territory that include common oak , sessile oak , cherry , lime , and ash . Other plants include: fescue , nettle , clover , peony , and more. Ocnița district
798-542: 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
855-419: 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
912-463: 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
969-400: 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
1026-436: Is an ongoing controversy regarding the ethnic identification of Moldovans and Romanians. Agriculture occupies a central role in the economy of the district. In farming district in recent years there have been radical changes in relations of production, related to the transition to a market economy, to abandon the methods of centralized rule, changing property relations and forms of management. From an institutional perspective,
1083-538: Is located in the basins of two rivers. The Nistru is in the east-central part, and runs through the district with a length with tributaries of 20–30 km. The Prut river basin is located in the south-western part of the district and has as tributaries in the upper part the Racovăț and the Ciuhur . 1 January 2012 the district population was 55,800 of which 35.0% urban and 65.0% rural population. Footnote : * There
1140-886: Is located in the so-called " Red North ", where, starting with the 2001 elections , the Party of Communists of the Republic of Moldova (PCRM) has been getting over 50% of the vote. For the last three elections, though, the Communists have been in constant decline. The district is one of the founding members of Euroregion Dniester . During the last three elections, the Alliance for European Integration (AEI) had an increase of 104% in votes. In Ocnița District are 32 educational institutions operating: in schools – 5482 children in agro-college – 242 in polyvalent vocational schools – 196. Currently in educational institutions operating in
1197-523: 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
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#17328014818741254-719: 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 the 14th century in Middle High German and in East Central German and which came from the Polish dialect term twardy , which corresponds to
1311-729: 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
1368-475: 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
1425-412: 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
1482-591: 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 the mineral to be a form of supercooled ice. Today,
1539-541: The Molotov–Ribbentrop Pact Bessarabia was occupied by the Soviet Union . In 2004 the district had 56,500 inhabitants. Ocnița district is located in northern Moldova; it borders with Briceni District to the west and with Edineț and Dondușeni districts to the south and southeast. To the north it borders Ukraine , between meridians 27°10′W and 27°50′W and 48°25′N. The most northerly point of
1596-524: 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
1653-620: 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,
1710-457: 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
1767-466: 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
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1824-499: The Republic of Moldova is located in Ocnița district: the village Naslavcea , with coordinates: 48°28′02″N, 27°35′04″W. In general, the terrain is characterized by plains and gentle hills. Over the many little rivers, valleys landforms gets injured. Here come the daylight limestone rocks, forming rocky areas, called Toltre. In district is extracted precious building materials: limestone , quartz sand , clay shale . The maximum altitude in
1881-496: The agricultural sector of the district is covered by a multitude of forms of organization and legal – 3 agricultural production cooperatives that process in 2448 ha of land, 3-stock holding companies 3508 ha, 28 limited liability companies with a total area of 13,328 hectares, 42 farms with a total area of 8458 ha and 3979 ha of farmland are processed individually. The district is in total 5015 registered companies. District Directorate of Agriculture and Food, orient their work towards
1938-441: 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
1995-407: 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
2052-444: 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
2109-466: 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
2166-433: 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
2223-460: The district 652 teachers. After the 2010 education reform is proposed to open more grammar schools and high schools is proposed closed all environments. The district Ocnița has six museums, 153 artistic works, 15 bands holding the title of the band model, 30 public libraries. The district Ocnița has two hospitals with general fund of 200 beds, a center of family doctors in the composition of which are 20 family physician offices, six health centers,
2280-426: The district is located near the village of Hădărăuți , reaching heights of 280 m (920 ft). Ocnița district has a temperate continental climate and the four seasons are well pronounced in winter is mild, spring – unstable and short summer – long and warm and the autumn – long and sunny. The average air temperature ranges from 7.5 to 10 °C (45 to 50 °F), positive temperature recorded in 165–200 days
2337-790: The following centuries the territory adjacent to the boundary of the district today is the Principality of Moldavia : Grand Duchy of Lithuania later the Polish-Lithuanian Union and Russian Empire . In 1812, the district and Bessarabia as a whole were occupied by the Russian Empire after the Treaty of Bucharest . In 1918 with the Union of Bessarabia with Romania , the area became part of Hotin County . In 1940, following
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2394-442: 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
2451-437: 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
2508-452: 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
2565-517: 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
2622-421: 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
2679-446: The organization and training of managers and professionals from large and small farms. An important role in achieving the expected results is agricultural machinery. Park tractors and agricultural machinery in the district consists of: Tractors – 450 units, combine – 78 un, seeder – 172 un, growing 190 un, watering – 46 un, combination – 10 un, plows – 201 un. Rail is the principal district to transport goods and fuel, but also
2736-578: The period 1422–1431 when the localities are listed first: Hădărăuți , Mihălășeni , Lipnic , Naslavcea and others. 20 August 1470, at Lipnic (Lipinți) was famous Battle of Lipnic , the river, where the Moldavian military , led by Stephen the Great , defeated the armies of the Crimean Khanate led by Murtada. After the fight Khan son and his brother Eminec are captured and taken as prisoners. In
2793-494: 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
2850-403: 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
2907-510: 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
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#17328014818742964-437: The routes to human transport: Chișinău , Bălți , Chernivtsi , Iași , Moscow, Kyiv , St. Petersburg and others. Bălți–Chernivtsi railway passing through the cities Otaci – Frunză – Ocnița was built between 1892 and 1897, when it is documented and targeted the railway station Ocnița built in 1897. Road transport is vital to passenger transport routes are more inter-regional, inter-republican and international. Ocnița district
3021-516: 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
3078-438: 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 the most commonly used minerals in the making of jewelry and hardstone carvings , especially in Europe and Asia. Quartz
3135-414: 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
3192-420: 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
3249-541: 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
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