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Athabascaite
Athabascaite is a member of the copper selenide minerals, and forms with other copper selenides. It was first discovered by S. Kaiman in 1949 while he was researching radioactive materials around Lake Athabasca. Kaiman was conducting research near Uranium City, Saskatchewan where mass amounts of uranium mines were present.Harris, D.C., Cabri, L.J., and Kaiman, S. (1970Athabascaite: A New Copper Selenide Mineral from Martin Lake, Saskatchewan The Canadian Mineralogist, 10(2), 207-215. History Kaiman sent his specimens for testing to J. W. Earley, then a graduate student. With the invention of the microprobe analyzer, D.C. Harris decided to delve further into the virtually unknown mineral with little success.Earley, J.W. (1950Description and Synthesis of the Selenide Minerals The American Mineralogist 35(5&6), 337-364. Structure Because of unavailability of sufficiently large single crystals, little is known about the atomic structure of athabascaite. Copper (Cu+) serves as the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Selenide Mineral
Selenide minerals are those minerals that have the selenide anion as a main component. Selenides are similar to sulfides and often grouped with them. Examples include: * achavalite * athabascaite * clausthalite * ferroselite * penroseite * stilleite * tiemannite * umangite Umangite is a copper selenide mineral, Cu3 Se2, discovered in 1891. It occurs only in small grains or fine granular aggregates with other copper minerals of the sulfide group. It has a hardness of 3. It is blue-black to red-violet in color with ... References {{Mineral-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Umangite
Umangite is a copper selenide mineral, Cu3 Se2, discovered in 1891. It occurs only in small grains or fine granular aggregates with other copper minerals of the sulfide group. It has a hardness of 3. It is blue-black to red-violet in color with a black streak. It has a metallic luster. Umangite is named after the locality of Sierra de Umango, La Rioja province in Argentina. It also occurs at other localities including the Harz Mountains in Germany, and at Skrickerum, Sweden. See also *List of minerals This is a list of minerals for which there are articles on Wikipedia. Minerals are distinguished by various chemical and physical properties. Differences in chemical composition and crystal structure distinguish the various ''species''. Within a m ... References Copper(I,II) minerals Selenide minerals Tetragonal minerals Minerals in space group 113 {{mineral-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vysočina Region
The Vysočina Region (; cs, Kraj Vysočina "Highlands Region", , ) is an administrative unit ( cs, kraj) of the Czech Republic, located partly in the south-eastern part of the historical region of Bohemia and partly in the south-west of the historical region of Moravia. Its capital is Jihlava. The region is the location of two mountain ranges, Žďárské vrchy and Jihlavské vrchy, both part of the Bohemian-Moravian Highlands. The Vysočina Region is home to three UNESCO World Heritage Sites, the most in any region in the Czech Republic. The region is one of just three in the country (the others being Prague and the Central Bohemian Region) which does not have a border with a foreign country. Administrative divisions The Vysočina Region is divided into 5 districts: On a lower level, the region has 704 municipalities, second-most in the country behind the Central Bohemian Region. Population As of 1 January 2019 the population of the Vysočina Region was 509,274, which w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Birefringence
Birefringence is the optical property of a material having a refractive index that depends on the polarization and propagation direction of light. These optically anisotropic materials are said to be birefringent (or birefractive). The birefringence is often quantified as the maximum difference between refractive indices exhibited by the material. Crystals with non-cubic crystal structures are often birefringent, as are plastics under mechanical stress. Birefringence is responsible for the phenomenon of double refraction whereby a ray of light, when incident upon a birefringent material, is split by polarization into two rays taking slightly different paths. This effect was first described by Danish scientist Rasmus Bartholin in 1669, who observed it in calcite, a crystal having one of the strongest birefringences. In the 19th century Augustin-Jean Fresnel described the phenomenon in terms of polarization, understanding light as a wave with field components in transverse pola ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reflectivity
The reflectance of the surface of a material is its effectiveness in reflecting radiant energy. It is the fraction of incident electromagnetic power that is reflected at the boundary. Reflectance is a component of the response of the electronic structure of the material to the electromagnetic field of light, and is in general a function of the frequency, or wavelength, of the light, its polarization, and the angle of incidence. The dependence of reflectance on the wavelength is called a ''reflectance spectrum'' or ''spectral reflectance curve''. Mathematical definitions Hemispherical reflectance The ''hemispherical reflectance'' of a surface, denoted , is defined as R = \frac, where is the radiant flux ''reflected'' by that surface and is the radiant flux ''received'' by that surface. Spectral hemispherical reflectance The ''spectral hemispherical reflectance in frequency'' and ''spectral hemispherical reflectance in wavelength'' of a surface, denoted and respectively, ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mohs Scale
The Mohs scale of mineral hardness () is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material. The scale was introduced in 1812 by the German geologist and mineralogist Friedrich Mohs, in his book ''"Versuch einer Elementar-Methode zur naturhistorischen Bestimmung und Erkennung der Fossilien"''; it is one of several definitions of hardness in materials science, some of which are more quantitative. The method of comparing hardness by observing which minerals can scratch others is of great antiquity, having been mentioned by Theophrastus in his treatise ''On Stones'', , followed by Pliny the Elder in his ''Naturalis Historia'', . The Mohs scale is useful for identification of minerals in the field, but is not an accurate predictor of how well materials endure in an industrial setting – ''toughness''. Minerals The Mohs scale of mineral hardness is based on the ability ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hardness
In materials science, hardness (antonym: softness) is a measure of the resistance to localized plastic deformation induced by either mechanical indentation or abrasion (mechanical), abrasion. In general, different materials differ in their hardness; for example hard metals such as titanium and beryllium are harder than soft metals such as sodium and metallic tin, or wood and common plastics. Macroscopic hardness is generally characterized by strong intermolecular bonds, but the behavior of solid materials under force is complex; therefore, hardness can be measured in different ways, such as scratch hardness, indentation hardness, and rebound hardness. Hardness is dependent on ductility, elasticity (physics), elastic stiffness, plasticity (physics), plasticity, deformation (mechanics), strain, strength of materials, strength, toughness, viscoelasticity, and viscosity. Common examples of hard matter are ceramics, concrete, certain metals, and superhard materials, which can be cont ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Recrystallization (geology)
In geology, solid-state recrystallization is a metamorphic process that occurs under high temperatures and pressures where atoms of minerals are reorganized by diffusion and/or dislocation glide. During this process, the physical structure of the minerals is altered while the composition remains unchanged. This is in contrast to metasomatism, which is the chemical alteration of a rock by hydrothermal and other fluids. Solid-state recrystallization can be illustrated by observing how snow recrystallizes to ice. When snow is subjected to varying temperatures and pressures, individual snowflakes undergo a physical transformation but their composition remains the same. Limestone is a sedimentary rock that undergoes metamorphic recrystallization to form marble, and clay Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4). Clays develop plasticity when wet, due to a molecular film of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lath
A lath or slat is a thin, narrow strip of straight-grained wood used under roof shingles or tiles, on lath and plaster walls and ceilings to hold plaster, and in lattice and trellis work. ''Lath'' has expanded to mean any type of backing material for plaster. This includes metal wire mesh or expanded metal that is applied to a wood or metal framework as matrix over which stucco or plaster is applied, as well as wallboard products called gypsum or rock lath.Ching, Frank. ''A visual dictionary of architecture''. New York: Van Nostrand Reinhold, 1995. 198. Print. Historically, reed mat was also used as a lath material. One of the key elements of lath, whether wooden slats or wire mesh, are the openings or gaps that allow plaster or stucco to ooze behind and form a mechanical bond to the lath. This is not necessary for gypsum lath, which relies on a chemical bond. Etymology The word is recorded from the late 13th century and is likely derived from the Old English word *, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Veinlets
A leaf ( : leaves) is any of the principal appendages of a vascular plant stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, flower, and fruit collectively form the shoot system. In most leaves, the primary photosynthetic tissue is the palisade mesophyll and is located on the upper side of the blade or lamina of the leaf but in some species, including the mature foliage of ''Eucalyptus'', palisade mesophyll is present on both sides and the leaves are said to be isobilateral. Most leaves are flattened and have distinct upper (adaxial) and lower (abaxial) surfaces that differ in color, hairiness, the number of stomata (pores that intake and output gases), the amount and structure of epicuticular wax and other features. Leaves are mostly green in color due to the presence of a compound called chlorophyll that is essential for photosynthesis as it absorbs light e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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