|
Joaquinite
Joaquinite-(Ce) is a rare silicate mineral with the chemical formula NaBa2Ce2Fe2+Ti2Si8O26(OH)·2H2O. It crystallizes in the monoclinic system with orthorhombic pseudomorphism and exhibits tabular crystals. Crystallography Joaquinite-(Ce) belongs to the monoclinic crystal system with orthorhombic pseudomorphism. It forms in point group 2. Twinning is polysynthetic on , and the mineral shows good cleavage on with uneven fracture. The average hardness is 5.5 on the Mohs scale The Mohs scale ( ) of mineral hardness is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of minerals through the ability of harder material to scratch softer material. The scale was introduced in 1812 by the Ger .... Optical properties The mineral is translucent, with a vitreous lustre and white streak. It is biaxial and displays strong red-brown pleochroism. Internally, it shows strong red-brown reflections under crossed polars. Environment Joaquinite ty ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neptunite
Neptunite is a silicate mineral with the formula K Na2 Li( Fe2+, Mn2+)2 Ti2 Si8 O24. With increasing manganese it forms a series with mangan-neptunite is the variety with vanadium replacing the titanium in the formula. It was first described in 1893 for an occurrence in the Narssârssuk pegmatite of West Greenland. It is also found within natrolite veins in glaucophane schist within serpentinite in San Benito County, California, US. It also occurs in Mont Saint-Hilaire, Quebec and in the Kola Peninsula of Russia. The mineral is named for Neptune, Roman god of the sea because of its association with aegirine from '' Àgir'', the Scandinavian sea-god. The Gemological Institute of America (GIA) identified an 11.78-carat faceted specimen as neptunite based on Raman spectroscopy Raman spectroscopy () (named after physicist C. V. Raman) is a Spectroscopy, spectroscopic technique typically used to determine vibrational modes of molecules, although rotational and other low-freq ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Benitoite
Benitoite () is a rare blue barium titanium cyclosilicate mineral, found in hydrothermally altered serpentinite. It forms in low temperature, high pressure environments typical of subduction zones at convergent plate boundaries. Benitoite fluoresces under short wave ultraviolet light, appearing bright blue to bluish white in color. The more rarely seen clear to white benitoite crystals fluoresce red under long-wave UV light. It was discovered in 1907 by prospector James M. Couch in the San Benito Mountains roughly halfway between San Francisco and Los Angeles. Due to its similar color, Couch originally believed it to be sapphire, a variety of corundum. In 1909, a sample was sent to the University of California, Berkeley, where mineralogist Dr. George D. Louderback realized it was a previously unknown mineral. Corundum (sapphire) has a defined Mohs hardness of 9, while benitoite is much softer. He named it ''benitoite'' for its occurrence near the headwaters of the San Benit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silicate Minerals
Silicate minerals are rock-forming minerals made up of silicate groups. They are the largest and most important class of minerals and make up approximately 90 percent of Earth's crust. In mineralogy, the crystalline forms of silica (silicon dioxide, ) are usually considered to be tectosilicates, and they are classified as such in the Dana system (75.1). However, the Nickel-Strunz system classifies them as oxide minerals (4.DA). Silica is found in nature as the mineral quartz, and its polymorphs. On Earth, a wide variety of silicate minerals occur in an even wider range of combinations as a result of the processes that have been forming and re-working the crust for billions of years. These processes include partial melting, crystallization, fractionation, metamorphism, weathering, and diagenesis. Living organisms also contribute to this geologic cycle. For example, a type of plankton known as diatoms construct their exoskeletons ("frustules") from silica extracted from s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gneiss
Gneiss (pronounced ) is a common and widely distributed type of metamorphic rock. It is formed by high-temperature and high-pressure metamorphic processes acting on formations composed of igneous or sedimentary rocks. This rock is formed under pressures ranging from 2 to 15 kbar, sometimes even more, and temperatures over 300 °C (572 °F). Gneiss nearly always shows a banded texture characterized by alternating darker and lighter colored bands and without a distinct Cleavage (geology), cleavage. Gneisses are common in the ancient crust of Continental Shield, continental shields. Some of the oldest rocks on Earth are gneisses, such as the Acasta Gneiss. Description image:Orthogneiss Geopark.jpg, Orthogneiss from the Czech Republic In traditional English and North American usage, a gneiss is a coarse-grained metamorphic rock showing compositional banding (gneissic banding) but poorly developed schistosity and indistinct Cleavage (geology), cleavage. In other words, it i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Baotite
{{Infobox mineral , name = Baotite , category = Cyclosilicate , image = Baotite-661893.jpg , imagesize = 260px , alt = , caption = Baotite from Sheep Creek, Mineral Point District, Ravalli County, Montana , formula = Ba4Ti4(Ti,Nb,Fe)4(Si4O12)O16Cl , IMAsymbol=Bao , molweight = , strunz = 9.CE.15 , system = Tetragonal , class = Dipyramidal (4/m) H-M symbol: (4/m) , symmetry = ''I''41/a , color = light brown to black , habit = anhedral to subhedral, prismatic and striated parallel to (001) , twinning = , cleavage = fair on {110} , fracture = hackly , tenacity = brittle , mohs = 6 , luster = vitreous , refractive = nω = 1.94,nε > 2.00 , opticalprop = Uniaxial (+) , birefringence = , dispersion = , pleochroism = strong , fluorescence= , absorption = E > O , streak = , gravity = , density = 4.42-4.71 g/mL (measured),4.69 g/mL (calculated) , fusibility = , diagnostic = , solubility = , diaphan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eudialyte
Eudialyte, whose name derives from the Greek phrase , , meaning "well decomposable", is a somewhat rare, nine-member-ring cyclosilicate mineral, which forms in alkaline igneous rocks, such as nepheline syenites. Its name alludes to its ready solubility in acid. Eudialyte was first described in 1819 for an occurrence in nepheline syenite of the Ilimaussaq intrusive complex of southwest Greenland. Uses Eudialyte is used as a minor ore of zirconium. Another use of eudialyte is as a minor gemstone, but this use is limited by its rarity, which is compounded by its poor crystal habit. These factors make eudialyte of primary interest as a collector's mineral. Eudialyte typically has a significant content of U, Pb, Nb, Ta, Zr, Hf, and rare earth elements (REE). Because of this, geoscientists use eudialyte as a geochronometer to date and investigate the genesis of the host rocks. Associated minerals Eudialyte is found associated with other alkalic igneous minerals, in addition to som ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
