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Helgustaðanáma
Helgustadir mine ( ) is a mine in the east of Iceland where Iceland spar (a form of transparent calcite) was mined from the mid-17th century to the 20th century. It is the source of the largest and clearest known Iceland spar specimen and the source of most museum specimens of Iceland spar. It was declared a nature reserve in 1975. About Location The mine is located near Eskifjörður, east of Iceland. Helgustadir mine consists of two mines, known as the upper and lower mine. Uses Crystals from this area are known for exceptional clarity, leading to the mineral being named "Iceland spar". Iceland spar from Helgustadir mine was used in optical devices used in physics, chemistry, and geology, most importantly Nicol prisms. Nature reserve The nature reserve is 0.9 hectares The hectare (; SI symbol: ha) is a non-SI metric unit of area equal to a square with 100-metre sides (1 hm2), that is, square metres (), and is primarily used in the measurement of land ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helgustaðanáma 2023
Helgustadir mine ( ) is a Mining, mine in the Eastern Region (Iceland), east of Iceland where Iceland spar (a form of transparent calcite) was mined from the mid-17th century to the 20th century. It is the source of the largest and clearest known Iceland spar specimen and the source of most museum specimens of Iceland spar. It was declared a nature reserve in 1975. About Location The mine is located near Eskifjörður, east of Iceland. Helgustadir mine consists of two mines, known as the upper and lower mine. Uses Crystals from this area are known for exceptional clarity, leading to the mineral being named "Iceland spar". Iceland spar from Helgustadir mine was used in optical devices used in physics, chemistry, and geology, most importantly Nicol prisms. Nature reserve The nature reserve is 0.9 hectares. Since 2010, it has been on the Environment Agency of Iceland's red list of areas that are likely to lose their protection status. Theft of crystals Being a nature ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iceland Spar
Iceland spar, formerly called Iceland crystal ( , ) and also called optical calcite, is a transparent variety of calcite, or crystallized calcium carbonate, originally brought from Iceland, and used in demonstrating the polarization of light. Formation and composition Iceland spar is a colourless, transparent variety of calcium carbonate (CaCO3). It crystallizes in the trigonal system, typically forming rhombohedral crystals.Hughes, H. Herbert., Iceland spar and optical fluorite: ''U. S. Bureau of Mines, Information Circular'' 6468 (1931) It has a Mohs hardness of 3 and exhibits double refraction, splitting a ray of light into two rays that travel at different speeds and directions. Iceland spar forms in sedimentary environments, mainly limestone and dolomite rocks, but it also forms in hydrothermal veins and evaporite deposits. It precipitates from solutions rich in calcium and carbonate ions, influenced by temperature, pressure, and impurities. The most common crystal stru ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mining
Mining is the Resource extraction, extraction of valuable geological materials and minerals from the surface of the Earth. Mining is required to obtain most materials that cannot be grown through agriculture, agricultural processes, or feasibly created Chemical synthesis, artificially in a laboratory or factory. Ores recovered by mining include Metal#Extraction, metals, coal, oil shale, gemstones, limestone, chalk mining, chalk, dimension stone, rock salt, potash, gravel, and clay. The ore must be a rock or mineral that contains valuable constituent, can be extracted or mined and sold for profit. Mining in a wider sense includes extraction of any non-renewable resource such as petroleum, natural gas, or even fossil water, water. Modern mining processes involve prospecting for ore bodies, analysis of the profit potential of a proposed mine, extraction of the desired materials, and final mine reclamation, reclamation or restoration of the land after the mine is closed. Mining ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eastern Region (Iceland)
Eastern Region (, ) is a region in eastern Iceland. Its area is and in 2024 its population was 11,085. The Eastern Region has a jagged coastline of fjords, referred to as the ''Eastfjords'' ( ). The largest town in the region is Egilsstaðir, with a population of 2,632. The oldest municipality is Djúpivogur, which got their trading licence in 1589 and had a population of 412 in 2024. The only car and passenger ferry that sails between Iceland and the European continent calls at Seyðisfjörður once a week except in the winter season. The region is home to the Kárahnjúkar Hydropower Plant Kárahnjúkar Hydropower Plant ( ), officially called Fljótsdalur Power Station ( ) is a hydroelectric power plant in Fljótsdalshérað municipality in eastern Iceland, designed to produce annually for Alcoa's Fjarðaál Aluminium smelting, alu .... Among notable tourist destinations are the Helgustaðir mine, which is known for its Iceland spar, and Stuðlagil. References See ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calcite
Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on the Mohs scale of mineral hardness, based on Scratch hardness, scratch hardness comparison. Large calcite crystals are used in optical equipment, and limestone composed mostly of calcite has numerous uses. Other polymorphs of calcium carbonate are the minerals aragonite and vaterite. Aragonite will change to calcite over timescales of days or less at temperatures exceeding 300 °C, and vaterite is even less stable. Etymology Calcite is derived from the German , a term from the 19th century that came from the Latin word for Lime (material), lime, (genitive ) with the suffix ''-ite'' used to name minerals. It is thus a Doublet (linguistics), doublet of the word ''wikt:chalk, chalk''. When applied by archaeology, archaeologists and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eskifjörður
Eskifjörður (in original spelling; ), or Eskifjördur, is a town and port in eastern Iceland with a large fishing industry. With a population of 1,043 it is one of the most populous towns in the municipality of Fjarðabyggð. History Eskifjörður had 302 inhabitants in 1901, 425 in 1910, 619 in 1920, 758 in 1930, 671 in 1940, 673 in 1950, 1741 in 1960, 936 in 1970 and 1 084 in 1981. It obtained the rights and privileges of an official trading place (''verslunastaður'') as early as 1786 und was awarded municipal status (''kaupstaðarréttindi'') on 10 April 1974. It developed into a booming community after Örum & Wulff, a powerful Danish trading company, had opened a trading post in 1798. In 1802 Kjartan Þórlaksson, the first Icelandic merchant who was not a Dane, settled down in Eskifjörður and started a successful business. Eskifjörður joined Neskaupstaður and Reyðarfjörður in 1998 to form the new municipality of Fjarðabyggð ("fjords-settlement"). Geography T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nicol Prism
A Nicol prism is a type of polarizer. It is an optical device made from calcite crystal used to convert ordinary light into plane polarized light. It is made in such a way that it eliminates one of the rays by total internal reflection, i.e. the ordinary ray is eliminated and only the extraordinary ray is transmitted through the prism. It was the first type of polarizing prism, invented in 1828 by William Nicol (1770–1851) of Edinburgh. Mechanism The Nicol prism consists of a rhombohedral crystal of Iceland spar (a variety of calcite) that has been cut at an angle of 68° with respect to the crystal axis, cut again diagonally, and then rejoined, using a layer of transparent Canada balsam as a glue. Unpolarized light ray enters through the side face of the crystal, and is split into two orthogonally polarized, differently directed rays by the birefringence property of calcite. The ''ordinary'' ray, or ''o''-ray, experiences a refractive index of ''n''o = 1.658 in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calcite Sample-Jenisch 91224-P4150799-black
Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on the Mohs scale of mineral hardness, based on scratch hardness comparison. Large calcite crystals are used in optical equipment, and limestone composed mostly of calcite has numerous uses. Other polymorphs of calcium carbonate are the minerals aragonite and vaterite. Aragonite will change to calcite over timescales of days or less at temperatures exceeding 300 °C, and vaterite is even less stable. Etymology Calcite is derived from the German , a term from the 19th century that came from the Latin word for lime, (genitive ) with the suffix ''-ite'' used to name minerals. It is thus a doublet of the word ''chalk''. When applied by archaeologists and stone trade professionals, the term alabaster is used not just as in geology and mineralogy, where it is reserved for a variety of g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hectares
The hectare (; SI symbol: ha) is a non-SI metric unit of area equal to a square with 100-metre sides (1 hm2), that is, square metres (), and is primarily used in the measurement of land. There are 100 hectares in one square kilometre. An acre is about and one hectare contains about . In 1795, when the metric system was introduced, the ''are'' was defined as 100 square metres, or one square decametre, and the hectare (" hecto-" + "are") was thus 100 ''ares'' or km2 ( square metres). When the metric system was further rationalised in 1960, resulting in the International System of Units (), the ''are'' was not included as a recognised unit. The hectare, however, remains as a non-SI unit accepted for use with the SI and whose use is "expected to continue indefinitely". Though the dekare/decare daa () and are (100 m2) are not officially "accepted for use", they are still used in some contexts. Description The hectare (), although not a unit of SI, is the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mindat
Mindat may refer to: Places * Mindat District, a district in Chin State, Myanmar (Burma), consisting of two townships and many villages ** Mindat Township, Myanmar *** Mindat, Chin State, a town in Chin State, Myanmar, administrative seat of Mindat Township Other uses * Mindat, alternative name for the Kʼchò language in Myanmar * Mindat Min, a Burmese prince * Mindat.org, an online mineralogy database {{dab, geo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
