Fettelite | |
---|---|
General | |
Category | Sulfosalt mineral |
Formula (repeating unit) | Ag16HgAs4S15 (rruff) or [Ag6As2S7]·[Ag10HgAs2S8] (mindat.org) |
IMA symbol | Ftt [1] |
Strunz classification | 2.LA.30 |
Crystal system | Monoclinic |
Crystal class | Sphenoidal (2) (same H-M symbol) |
Space group | C2 |
Unit cell | a = 15.00, c = 15.46 [Å] V = 3014 Å3; Z = 8 |
Identification | |
Color | dark violet to red |
Crystal habit | flakes, hexagonal, micaceous |
Twinning | intimately twinned with six twin domains |
Cleavage | perfect |
Fracture | subconchoidal |
Mohs scale hardness | 3.5 |
Luster | metallic |
Streak | dark vermillion |
Diaphaneity | subopaque to opaque |
Specific gravity | 6.29 |
Optical properties | Biaxial, anisotrophism weak with strong red internal reflections |
Refractive index | N(calc) = 1.74 |
Birefringence | moderate white to brownish gray |
References | [2] [3] [4] |
Fettelite, also known as sanguinite, is a mercury-sulfosalt mineral with the chemical formula Ag16HgAs4S15. The mineral was first described by Wang and Paniagua (1996) [5] who named it after M. Fettel, a German field geologist who collected the first samples from Odenwald. [6] It was first collected in the Nieder-Beerbach mine, 10 km south of Darmstadt, Odenwald, Germany. Its normal occurrence is in hydrothermal veins, which can cut gabbro-diorite intrusives. It is closely related to other rare minerals like dervillite, daomanite, vaughanite and criddleite which are also found in the same type locality as fettelite. [4]
Fettelite occurs as clusters of hexagonal flakes. These flakes can get up to 0.2 mm across and around 5-10 µm thick. In more complex hexagonal tablets, somewhat larger sub parallel aggregates can be measured. [7] The birefringence of Fettelite is moderate white to grayish brown. [6]
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). Both of the chemically similar gold-silver tellurides, calaverite and sylvanite, are in the monoclinic crystal system, whereas krennerite is orthorhombic.
Jamesonite is a sulfosalt mineral, a lead, iron, antimony sulfide with formula Pb4FeSb6S14. With the addition of manganese it forms a series with benavidesite. It is a dark grey metallic mineral which forms acicular prismatic monoclinic crystals. It is soft with a Mohs hardness of 2.5 and has a specific gravity of 5.5 - 5.6. It is one of the few sulfide minerals to form fibrous or needle like crystals. It can also form large prismatic crystals similar to stibnite with which it can be associated. It is usually found in low to moderate temperature hydrothermal deposits.
Polybasite is a sulfosalt mineral of silver, copper, antimony and arsenic. Its chemical formula is [(Ag,Cu)6(Sb,As)2S7][Ag9CuS4].
Routhierite is a rare thallium sulfosalt mineral with formula Tl(Cu,Ag)(Hg,Zn)2(As,Sb)2S6.
Temagamite is a bright white palladium mercury telluride mineral with a hardness of 2+1⁄2 on the Mohs scale. Its chemical formula is Pd3HgTe3. It was discovered at the Temagami Mine on Temagami Island, Lake Temagami in 1973, and it represents a rare mineral in the Temagami Greenstone Belt.
Godovikovite is a rare sulfate mineral with the chemical formula: (NH4)Al(SO4)2. Aluminium can partially be substituted by iron. Hydration of godovikovite gives the ammonium alum, tschermigite. The mineral forms cryptocrystalline, often porous, masses, usually of white colour. Single crystals are very small hexagonal blades. Typical environment for godovikovite are burning coal sites (mainly dumps). There the mineral acts, together with millosevichite, as one of the main components of so-called sulfate crust.
Aktashite is a rare arsenic sulfosalt mineral with formula Cu6Hg3As4S12. It is a copper mercury-bearing sulfosalt and is the only sulfosalt mineral with essential Cu and Hg yet known. It is of hydrothermal origin. It was published without approval of the IMA-CNMNC, but recognized as valid species by the IMA-CNMNC Sulfosalts Subcommittee (2008).
Galkhaite is a rare and chemically complex sulfosalt mineral from a group of natural thioarsenites. Its formula is (Cs,Tl)(Hg,Cu,Zn)6(As,Sb)4S12, making the mineral the only known natural Cs-Hg and Cs-As phase. It occurs in Carlin-type hydrothermal deposits.
Alacránite (As8S9) is an arsenic sulfide mineral first discovered in the Uzon caldera, Kamchatka, Russia. It was named for its occurrence in the Alacrán silver/arsenic/antimony mine. Pampa Larga, Chile. It is generally more rare than realgar and orpiment. Its origin is hydrothermal. It occurs as subhedral to euhedral tabular orange to pale gray crystals that are transparent to translucent. It has a yellow-orange streak with a hardness of 1.5. It crystallizes in the monoclinic crystal system. It occurs with realgar and uzonite as flattened and prismatic grains up to 0.5 mm across.
Aleksite (IMA symbol: Alk) is a rare lead bismuth tellurium sulfosalt mineral with formula PbBi2Te2S2.
Andorite is a sulfosalt mineral with the chemical formula PbAgSb3S6.
Gabrielite is a rare thallium sulfosalt mineral with a chemical formula of Tl6Ag3Cu6(As,Sb)9S21 or Tl2AgCu2As3S7.
Madocite is a mineral with a chemical formula of Pb17(Sb,As)16S41. Madocite was named for the locality of discovery, Madoc, Ontario, Canada. It is found in the marbles of the Precambrian Grenville Limestone. It is orthorhombic and in the point group mm2. Its crystals are elongated and striated along [001] to a size of 1.5 mm.
Abramovite is a very rare mineral from the sulfides and sulfosalt categories. It has the chemical formula Pb2SnInBiS7. It occurs as tiny elongated lamellar-shaped crystals, up 1 mm × 0.2 mm in size, and is characterized by its non-commensurate structure.
Ardaite is a very rare sulfosalt mineral with chemical formula Pb19Sb13S35Cl7 in the monoclinic crystal system, named after the Arda River, which passes through the type locality. It was discovered in 1978 and approved by the International Mineralogical Association in 1980. It was the second well-defined natural chlorosulfosalt, after dadsonite.
Daubréelite is a rare sulfide mineral. It crystallizes with cubic symmetry and has chemical composition of Fe2+Cr3+2S4. It usually occurs as black platy aggregates.
Playfairite is a rare sulfosalt mineral with chemical formula Pb16Sb18S43 in the monoclinic crystal system, named after the Scottish scientist and mathematician John Playfair. It was discovered in 1966 by the Canadian mineralogist John Leslie Jambor. Lead gray to black in color, its luster is metallic. Playfairite shows strong reflection pleochroism from white to brownish gray. Playfairite has a hardness of 3.5 to 4 on Mohs scale and a specific gravity of approximately 5.72.
Xanthoconite is a sulfosalt mineral with the chemical formula Ag3AsS3.
Argentopyrite is a moderately rare sulfide mineral with the chemical formula AgFe2S3. It is one of the natural compounds of the MFe2S3 type, with M being caesium in very rare pautovite, copper in relatively common cubanite, potassium in rare rasvumite and thallium in rare picotpaulite. The type locality is Jáchymov in Czech Republic. Chemically similar mineral include sternbergite, lenaite, AgFeS2, and argentopentlandite, Ag(Fe,Ni)8S8.
Danielsite is a sulfide and sulfosalt that was first discovered in a pocket of supergene minerals in the north region of Western Australia. The location found was about 1 kilometre (0.62 mi) west of the locality known as Coppin Pool. The mineral danielsite was named after John L. Daniels who collected the sample in which the new mineral was found. The chemical formula of danielsite is (Cu,Ag)
14HgS
8. Danielsite is very fine grained and hard to observe in hand samples. It generally has a gray color with very brittle and soft physical characteristics.