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43-675: The Roßtrappe rises over the Bode Gorge in the Harz. It may be reached from Thale by road, on foot or on via the Rosstrappe Chair Lift . On the rocks is a mountain hotel with an observation terrace as well as the upper station for the chair lift. Nearby is the Winzenburg , a refuge castle 25 hectares (62 acres) in area with a 500-metre-long (1,600 ft) rampart made of stone blocks and earth, which has been used since

86-635: A 150 m high dam at the Bodekessel . The plan was scrapped. Only a few streams enter the Bode, on the right-hand side of the ravine. The Luppbode is a lively, bubbling brook coming from the direction of Allrode which joins the Bode near Treseburg. Another tributary stream is the Dambach, which empties into the Bode from a side ravine below the Rabenstein. There is a rapid succession of habitats in

129-475: A carpet. Common toothwort ( Lathraea squamaria ) and spring snowflake ( Leucojum vernum ) also occur here and there. Perennial honesty ( Lunaria rediviva ) and large white buttercup ( Ranunculus platanifolius ) may be found in places in the woods. The Bode Gorge ist also a habitat and refuge for many types of rare animal. Such rarities include the wildcat , Bechstein's bat , peregrine falcon , black stork , middle spotted woodpecker . The insect fauna

172-436: A giant by the name of Bodo once followed the king’s beautiful daughter, Brunhilde , whom he wanted to marry against her will. Brunhilde escaped on a white stallion ( German : Ross ), but was suddenly confronted by a deep ravine. Her horse leapt in one bound to the rocks on the other side, but her pursuer fell into the depths below. The impression of the horse’s hoof may still be seen today. The giant Bodo gave his name to

215-435: A light microscope, whereas cryptoperthitic textures can be seen only with an electron microscope. Buddingtonite is an ammonium feldspar with the chemical formula: NH 4 AlSi 3 O 8 . It is a mineral associated with hydrothermal alteration of the primary feldspar minerals. Barium feldspars form as the result of the substitution of barium for potassium in the mineral structure. Barium feldspars are sometimes classified as

258-473: A mild abrasive action. The USGS estimated global production of feldspar in 2020 to be 26 million tonnes, with the top four producing countries being: China 2 million tonnes; India 5 million tonnes; Italy 4 million; Turkey 7.6 million tonnes. Typical mineralogical and chemical analyses of three commercial grades used in ceramics are: In October 2012, the Curiosity rover found high feldspar content in

301-399: A separate group of feldspars, and sometimes they are classified as a sub-group of alkali feldspars. The barium feldspars are monoclinic and include the following: The plagioclase feldspars are triclinic . The plagioclase series follows (with percent anorthite in parentheses): Intermediate compositions of exsolve to two feldspars of contrasting composition during cooling, but diffusion

344-616: A short distance in cold and/or dry conditions that did not promote weathering, and that it was quickly buried by other sediment. Sandstones with large amounts of feldspar are called arkoses . Feldspar is a common raw material used in glassmaking, ceramics, and to some extent as filler and an extender in paint, plastics, and rubber. In the US, about 66% of feldspar is consumed in glassmaking, including glass containers and glass fibre. Ceramics (including electrical insulators, sanitaryware, tableware and tile) and other uses, such as fillers, accounted for

387-725: A source of alkalies and alumina in glazes. The composition of feldspar used in different ceramic formulations varies depending on various factors, including the properties of the individual grade, the other raw materials and the requirements of the finished products. However, typical additions include: tableware, 15% to 30% feldspar; high-tension electrical porcelains, 25% to 35%; sanitaryware, 25%; wall tile, 0% to 10%; and dental porcelain up to 80% feldspar. Earth sciences : In earth sciences and archaeology, feldspars are used for potassium-argon dating , argon-argon dating and luminescence dating . Minor use : Some household cleaners (such as Bar Keepers Friend and Bon Ami ) use feldspar to give

430-476: A three-dimensional network. Compositions of major elements in common feldspars can be expressed in terms of three endmembers : Solid solutions between K-feldspar and albite are called alkali feldspar. Solid solutions between albite and anorthite are called plagioclase , or, more properly, plagioclase feldspar. Only limited solid solution occurs between K-feldspar and anorthite, and in the two other solid solutions, immiscibility occurs at temperatures common in

473-544: Is about 140 m deep at Treseburg and some 280 m deep at Thale where it breaks out into the Harz Foreland . The Bode Gorge was designated a nature reserve as early as 5 March 1937; its boundaries being subsequently expanded. With an area of, currently 473.78 hectares (1,170.7 acres), it is one of the largest nature reserves in Saxony-Anhalt . Apart from intrusions of Ramberg granite, which rose to

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516-435: Is characterised by fast-flowing, clean, shady stretches of river. In addition to brown trout it ish also home to loach , bullhead , three-spined stickleback and minnow . Rare visitors include pike , dace and perch . Rainbow trout have been introduced by anglers . The Bode Gorge may only be passed through on foot. A cycle path or bridleway is not feasible due to the narrowness of the ravine. Climbing and walking off

559-451: Is kinked. Each crankshaft chain links to neighbouring crankshaft chains to form a three-dimensional network of fused four-member rings. The structure is open enough for cations (typically sodium, potassium, or calcium) to fit into the structure and provide charge balance. Chemical weathering of feldspars happens by hydrolysis and produces clay minerals , including illite , smectite , and kaolinite . Hydrolysis of feldspars begins with

602-667: Is known as anorthosite . Feldspars are also found in many types of sedimentary rocks . The name feldspar derives from the German Feldspat , a compound of the words Feld ("field") and Spat ("flake"). Spat had long been used as the word for "a rock easily cleaved into flakes"; Feldspat was introduced in the 18th century as a more specific term, referring perhaps to its common occurrence in rocks found in fields (Urban Brückmann, 1783) or to its occurrence as "fields" within granite and other minerals (René-Just Haüy, 1804). The change from Spat to -spar

645-449: Is much slower than in alkali feldspar, and the resulting two-feldspar intergrowths typically are too fine-grained to be visible with optical microscopes. The immiscibility gaps in the plagioclase solid solutions are complex compared to the gap in the alkali feldspars. The play of colours visible in some feldspar of labradorite composition is due to very fine-grained exsolution lamellae known as Bøggild intergrowth. The specific gravity in

688-513: Is particularly varied. The white-throated dipper and grey wagtail can be observed hunting for insects on the stream beds. Mallard breed here and there in the reed beds or on remote gravel beds. In spring fire salamanders can be seen splashing about in the Bode Gorge during the spawning season. Care must be taken when walking not to disturb them. Where it flows through the gorge, the Bode ,

731-539: The Harzer Wandernadel walking trail network. Since the middle of the 19th century there has been a mountain hotel with the same name at the entrance to the Roßtrappe . 51°44′06″N 11°01′04″E  /  51.73500°N 11.01778°E  / 51.73500; 11.01778 Bode Gorge The Bode Gorge ( German : Bodetal ) is a 10 kilometres (6.2 mi) long ravine that forms part of

774-720: The Bode valley between Treseburg and Thale in the Harz Mountains of central Germany. The German term, Bodetal (literally "Bode Valley"), is also used in a wider sense to refer to the valleys of the Warme and Kalte Bode rivers that feed the River Bode. At the Bode Gorge, the River Bode , which rises on the highest mountain in the Harz, the Brocken , has cut deeply into the hard Ramberg granite rock. The ravine

817-790: The New Stone Age as a refuge for up to 100 people. In 1860 the Winzenburg Tower was built there; an observation tower which is now closed. From the Rosstrappe there is a view of the rocks on the Hexentanzplatz , ("Witches Dance Floor") the Steinerne Kirche ("Stone Church"), the Bode Gorge, the Harz Foreland, the town of Thale and the highest peak in the Harz, the Brocken . According to legend,

860-631: The granite rocks . Plants such as the snowy mespilus ( Amelanchier ovalis ), dyer’s greenweed ( Genista tinctoria ), browntop bent ( Agrostis capillaris ), sticky catchfly ( Lychnis viscaria ), blue stonecrop ( Sedum reflexum ) are particularly common. The scenery in spring is graced by wood anemones ( Anemone nemorosa ) and yellow anemones ( Anemone ranunculoides ), hollowroot ( Corydalis cava ), spring vetchling ( Lathyrus vernus ), kidneywort ( Hepatica nobilis ) and alternate-leaved golden saxifrage ( Chrysosplenium alternifolium ), which grows on stream banks, but also covers scree slopes like

903-426: The Bode Gorge that produces a tightly woven mosaic of vegetation, characterised by an especially rich variety of plant species. The most common trees in the woods are sessile oak ( Quercus petraea ), large-leaved lime ( Tilia platyphyllos ), sycamore ( Acer pseudoplatanus ), silver birch ( Betula pendula ) and rowan ( Sorbus aucuparia ). Also worth mentioning is the common yew ( Taxus baccata ). Dominating

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946-515: The Earth's crust means that clays are very abundant weathering products. About 40% of minerals in sedimentary rocks are clays and clays are the dominant minerals in the most common sedimentary rocks, mudrocks . They are also an important component of soils . Feldspar that has been replaced by clay looks chalky compared to more crystalline and glassy unweathered feldspar grains. Feldspars, especially plagioclase feldspars, are not very stable at

989-420: The Earth's surface due to their high formation temperature. This lack of stability is why feldspars are easily weathered to clays. Because of this tendency to weather easily, feldspars are usually not prevalent in sedimentary rocks. Sedimentary rocks that contain large amounts of feldspar indicate that the sediment did not undergo much chemical weathering before being buried. This means it was probably transported

1032-541: The Königsruhe tavern, is shrouded in legend. It was a low waterfall before its explosive demolition in 1798. Stones and boulders occupy the river bed. Slow-moving stretches of water occur, especially in the area of the Hornfels ( Zahme Bode ); rapids ( Wilde Bode ) are found particularly in the lower part of the ravine and formed by the incision of the river into the blocks of Ramberg granite . The water regime inside

1075-464: The alkali feldspars occur only in higher temperature environments. Sanidine is stable at the highest temperatures, and microcline at the lowest. Perthite is a typical texture in alkali feldspar, due to exsolution of contrasting alkali feldspar compositions during cooling of an intermediate composition. The perthitic textures in the alkali feldspars of many granites can be seen with the naked eye. Microperthitic textures in crystals are visible using

1118-443: The continuous Bowen's reaction series . K-feldspar is the final feldspar to crystallize from the magma. Alkali feldspars are grouped into two types: those containing potassium in combination with sodium, aluminium, or silicon; and those where potassium is replaced by barium. The first of these include: Potassium and sodium feldspars are not perfectly miscible in the melt at low temperatures, therefore intermediate compositions of

1161-474: The crust of the Earth. Albite is considered both a plagioclase and alkali feldspar. The ratio of alkali feldspar to plagioclase feldspar, together with the proportion of quartz , is the basis for the QAPF classification of igneous rock. Calcium-rich plagioclase is the first feldspar to crystallize from cooling magma, then the plagioclase becomes increasingly sodium-rich as crystallization continues. This defines

1204-465: The edges of the gorge. In the area of the ravine the Bode has a width of 7 to 25 metres and descends 100 metres in 17 kilometres. Its river course and bed are very much in their natural state inside the ravine. Kettle-holes, rapids and scouring in the rock alternate with islands of gravel and flat river banks. The most notable rapids on the Bode, the Bodekessel , not far southwest of

1247-429: The feldspar dissolving in water, which happens best in acidic or basic solutions and less well in neutral ones. The speed at which feldspars are weathered is controlled by how quickly they are dissolved. Dissolved feldspar reacts with H or OH ions and precipitates clays. The reaction also produces new ions in solution, with the variety of ions controlled by the type of feldspar reacting. The abundance of feldspars in

1290-486: The feldspar group are the plagioclase (sodium-calcium) feldspars and the alkali (potassium-sodium) feldspars. Feldspars make up about 60% of the Earth's crust and 41% of the Earth's continental crust by weight. Feldspars crystallize from magma as both intrusive and extrusive igneous rocks and are also present in many types of metamorphic rock . Rock formed almost entirely of calcic plagioclase feldspar

1333-507: The ground cover are plants like the wood bluegrass ( Poa nemoralis ), wavy hair-grass ( Avenella flexuosa ; especially in dry oak woods), white wood-rush ( Luzula luzuloides ), male fern ( Dryopteris filix-mas ), limestone oak fern ( Gymnocarpium robertianum ), wall hawkweed ( Hieracium murorum ), baneberry ( Actaea spicata ), small balsam ( Impatiens parviflora ), Herb Robert ( Geranium robertianum ), dog's mercury ( Mercurialis perennis ). A special plant community has grown on

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1376-475: The order they occur along the Bode Gorge from Thale to Treseburg. 51°44′08″N 11°00′35″E  /  51.73556°N 11.00972°E  / 51.73556; 11.00972 Feldspar Feldspar ( / ˈ f ɛ l ( d ) ˌ s p ɑːr / FEL(D) -spar ; sometimes spelled felspar ) is a group of rock-forming aluminium tectosilicate minerals , also containing other cations such as sodium, calcium, potassium, or barium. The most common members of

1419-422: The path, mountain biking, canyoning, water walking and whitewater canoeing or rafting are banned in order to protect the wildlife and biotope . Tourist facilities, restaurants and overnight accommodation are located at Thale by the entrance to the Bode Gorge. A ten kilometre long footpath runs through the Bode Gorge between Thale and Treseburg. At pinch points the path is routed in steep zigzags and walkways over

1462-488: The plagioclase series increases from albite (2.62) to anorthite (2.72–2.75). The structure of a feldspar crystal is based on aluminosilicate tetrahedra. Each tetrahedron consists of an aluminium or silicon ion surrounded by four oxygen ions. Each oxygen ion, in turn, is shared by a neighbouring tetrahedron to form a three-dimensional network. The structure can be visualized as long chains of aluminosilicate tetrahedra, sometimes described as crankshaft chains because their shape

1505-404: The ravine and characterises its highest rocks. It appears light-coloured due to the high proportion of white feldspar . The quartz lends it a grey shade. The proportion of black mica ( biotite ) is low and carries no weight in terms of colouring. The light-coloured granite stands out from the dark to black coloured rocks of hornfels and argillite. As a result, the front section of the ravine and

1548-541: The ravine between, for example, the sunny, warm and dry southern slopes and the more shaded, cooler and damper northern slopes and valley floor, modify the local climate considerably. The most common soil types are silicate leptosols , that belong to the thin stony soils around areas of rock and scree. In flatter areas with less rearrangement of the soil particles are stony Ranker leptosols of various thickness. One particular soil type, brown Ranker occurs above argillite rock. Podsolised brown earth soils are found around

1591-530: The ravine is affected, however, by the dams owned by the Bodewerk in the upper reaches of the river. The discharge can vary sharply: during the devastating New Year floods of 1925 a discharge of 350 m /s was recorded; in the summer of 1926 the Bode almost ran dry (0.,35 m /s). Other major floods occurred in 1667, 1730 and in April 1984. There was a plan to impound the Bode in the ravine as well in 1891 with

1634-487: The remainder. Glass : Feldspar provides both K 2 O and Na 2 O for fluxing, and Al 2 O 3 and CaO as stabilizers. As an important source of Al 2 O 3 for glassmaking, feldspar is valued for its low iron and refractory mineral content, a low cost per unit of Al 2 O 3 , no volatiles and no waste. Ceramics : Feldspars are used in the ceramic industry as a flux to form a glassy phase in bodies during firing, and thus promote vitrification. They also are used as

1677-458: The river bed of the Bode in this area appear clearly lighter than the rear section. The argillite at the rear of the gorge shows bands of colour in places that evinces the former strata of the marine sediments . The stratified slate was only slightly metamorphosed . In the area of the Bode Gorge average annual temperatures range from 8 °C down to 6.5 °C and annual precipitation between 600 and 720 mm. But sharp, local differences in

1720-490: The rocks. From them there are superb views into the ravine. Paths lead down into the gorge from the observation rocks at Rosstrappe and the Hexentanzplatz ("Witches' Dance Floor"). From the latter there is also a ridgeway to Treseburg. The Bode Gorge receives hundreds of thousands of visitors per year and is one of the leading tourist destinations in Saxony-Anhalt. The following places of interest are listed in

1763-481: The small river, the Bode . Scientists suspect that this imprint in the rock is the weathered remains of a Germanic altar basin. From the Roßtrappe visitors can climb down into the Bode Gorge on the Schurre , a path laid in zigzags. The President’s Way ( Präsidentenweg ), about 4 km, is the recommended path to climb from the gorge to the rock outcrop. The Roßtrappe is no. 71 in the system of check points on

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1806-561: The surface and solidified 300 million years ago in the Upper Carboniferous Period, and their associated veins of quartz , the ravine of the Bode also cuts through hornfels and knotenschiefer (a type of slate ), as well as argillite and graywacke with quartz elements and diabase dikes from the Devonian Period, 400 to 370 million years ago. Ramberg granite predominantly forms the front section of

1849-595: Was influenced by the English word spar , meaning a non-opaque mineral with good cleavage. Feldspathic refers to materials that contain feldspar. The alternate spelling, felspar , has fallen out of use. The term 'felsic', meaning light coloured minerals such as quartz and feldspars, is an acronymic word derived from fel dspar and si lica, unrelated to the obsolete spelling 'felspar'. The feldspar group of minerals consists of tectosilicates , silicate minerals in which silicon ions are linked by shared oxygen ions to form

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