Krennerite | |
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General | |
Category | Telluride mineral |
Formula (repeating unit) | AuTe2 to Au3AgTe8 |
IMA symbol | Knn [1] |
Strunz classification | 2.EA.15 |
Crystal system | Orthorhombic |
Crystal class | Pyramidal (mm2) |
Space group | Orthorhombic H-M symbol: (mm2) Space group: Pma2 |
Identification | |
Color | Silver white to brass yellow (tarnish?) – creamy white (polished section) |
Crystal habit | Massive to crystalline with short striated prismatic crystals |
Cleavage | Perfect on {001} |
Fracture | Subconchoidal – uneven |
Tenacity | Brittle |
Mohs scale hardness | 2.5 |
Luster | High metallic |
Streak | greenish grey |
Diaphaneity | opaque |
Specific gravity | 8.62 |
Optical properties | Anisotrophism strong |
Refractive index | Opaque |
Pleochroism | weak |
Ultraviolet fluorescence | None |
References | [2] [3] [4] |
Krennerite is an orthorhombic gold telluride mineral which can contain variable amounts of silver in the structure. The formula is AuTe2, but specimen with gold substituted by up to 24% with silver have been found ([Au0.77Ag0.24]Te2). [2] Both of the chemically similar gold-silver tellurides, calaverite and sylvanite, are in the monoclinic crystal system, whereas krennerite is orthorhombic.
The color varies from silver-white to brass-yellow. It has a specific gravity of 8.62 and a hardness of 2.5. It occurs in high temperature, hydrothermal environments.
Krennerite was discovered in 1878 near the village of Săcărâmb, Romania, and first described by the Hungarian mineralogist Joseph Krenner (1839–1920). [4]
Bornite, also known as peacock ore, is a sulfide mineral with chemical composition Cu5FeS4 that crystallizes in the orthorhombic system (pseudo-cubic).
The mineral petzite, Ag3AuTe2, is a soft, steel-gray telluride mineral generally deposited by hydrothermal activity. It forms isometric crystals, and is usually associated with rare tellurium and gold minerals, often with silver, mercury, and copper.
Calaverite, or gold telluride, is an uncommon telluride of gold, a metallic mineral with the chemical formula AuTe2, with approximately 3% of the gold replaced by silver. It was first discovered in Calaveras County, California in 1861, and was named for the county in 1868.
Sylvanite or silver gold telluride, chemical formula (Ag,Au)Te2, is the most common telluride of gold.
Painite is a very rare borate mineral. It was first found in Myanmar by British mineralogist and gem dealer Arthur C.D. Pain who misidentified it as ruby, until it was discovered as a new gemstone in the 1950s. When it was confirmed as a new mineral species, the mineral was named after him. Due to its rarity, painite can cost between US$50,000 to $60,000 per carat.
Weissite is a telluride mineral, a copper telluride. Its chemical formula is Cu
2−xTe. Weissite has hexagonal crystal structure. Its specific gravity is 6 and its Mohs hardness is 3. Occurrence is in Gunnison County, Colorado, Arizona and New Mexico in the United States. It is also reported from Kalgoorlie, Western Australia and Dalarna and Värmland, Sweden.
Empressite is a mineral form of silver telluride, AgTe. It is a rare, grey, orthorhombic mineral with which can form compact masses, rarely as bipyramidal crystals.
Seamanite, named for discoverer Arthur E. Seaman, is a rare manganese boron phosphate mineral with formula Mn3[B(OH)4](PO4)(OH)2. The yellow to pink mineral occurs as small, needle-shaped crystals. It was first discovered in 1917 from a mine in Iron County, Michigan, United States and identified in 1930. As of 2012, seamanite is known from four sites in Michigan and South Australia.
Aguilarite is an uncommon sulfosalt mineral with formula Ag4SeS. It was described in 1891 and named for discoverer Ponciano Aguilar.
Vulcanite is a rare copper telluride mineral. The mineral has a metallic luster, and has a green or bronze-yellow tint. It has a hardness between 1 and 2 on the Mohs scale. Its crystal structure is orthorhombic.
Gold chalcogenides are compounds formed between gold and one of the chalcogens, elements from group 16 of the periodic table: oxygen, sulfur, selenium, or tellurium.
Coloradoite, also known as mercury telluride (HgTe), is a rare telluride ore associated with metallic deposit. Gold usually occurs within tellurides, such as coloradoite, as a high-finess native metal.
Gonnardite is a comparatively rare, fibrous zeolite, natrolite subgroup. Older papers claim that a complete solid solution exists between tetranatrolite and gonnardite, but tetranatrolite was discredited as a separate species in 1999. A series, based on the disorder of the silicon-aluminum in the framework, appears to exist between Na-rich gonnardite and natrolite, Na2(Si3Al2)O10·2H2O.
Grandreefite is a rare secondary lead sulfate-fluoride mineral with a general chemical formula, Pb2SO4F2. It is named for the location in which it was discovered in 1989, the Grand Reef Mine in Graham County, Arizona.
Stützite or stuetzite is a silver telluride mineral with formula: Ag5−xTe3 (with x = 0.24 to 0.36) or Ag7Te4.
Kostovite is a rare orthorhombic-pyramidal gray white telluride mineral containing copper and gold with chemical formula AuCuTe4.
The mineral uytenbogaardtite, Ag3AuS2, is a soft, greyish white sulfide mineral, occurring in hydrothermal Au-Ag-quartz veins. It occurs as tiny crystals, visible only with a microscope. It has a metallic luster and a hardness on the Mohs scale of 2 (gypsum).
Filipstadite is a very rare mineral of the spinel group, with the formula (Mn,Mg)(Sb5+0.5Fe3+0.5)O4. It is isometric, although it was previously though to be orthorhombic. When compared to a typical spinel, both the octahedral and tetrahedral sites are split due to cation ordering. Filipstadite is chemically close to melanostibite. The mineral comes from Långban, Sweden, a manganese skarn deposit famous for many rare minerals.
Khinite is a rare tellurate mineral with the formula Pb2+Cu2+3TeO6(OH)2. It crystallizes in the orthorhombic system and has a bottle-green colour. It is often found as dipyramidal, curved or corroded crystals no more than 0.15 mm in size. The tetragonal dimorph of khinite is called parakhinite.
Ramsdellite (Mn4+O2) is an orthorhombic manganese dioxide mineral. It is relatively uncommon, and is usually found in deposits containing other manganese oxide crystals.