Guettardite
| Guettardite | |
|---|---|
| General | |
| Category | Sulfosalt mineral |
| Formula (repeating unit) | Pb(Sb,As)2S4 |
| IMA symbol | Gue[1] |
| Strunz classification | 2.HC.05a |
| Crystal system | Monoclinic |
| Crystal class | Prismatic (2/m) (same H-M symbol) |
| Space group | P21/a |
| Unit cell | a = 20.17, b = 7.94 c = 8.72 [Å]; β = 101.12°; Z = 8 |
| Identification | |
| Color | Grayish black; white with reddish internal reflections in polished section |
| Crystal habit | Acicular crystals and anhedral grains |
| Twinning | Polysynthetic twinning on {100} |
| Cleavage | Perfect on {001} |
| Fracture | Conchoidal |
| Tenacity | Very brittle |
| Mohs scale hardness | 4 |
| Luster | Metallic |
| Streak | Brown |
| Diaphaneity | Opaque |
| Specific gravity | 5.2 |
| Pleochroism | Relatively strong |
| References | [2][3][4] |
Guettardite is a rare arsenic-antimony lead sulfosalt mineral with the chemical formula Pb(Sb,As)2S4. It forms gray black metallic prismatic to acicular crystals with monoclinic symmetry. It is a dimorph of the triclinic .
Discovery and occurrence[]
It was first described in 1967 for an occurrence in the Taylor Pit, Madoc, Hastings County, Ontario, Canada. It was named for French naturalist Jean-Étienne Guettard (1715–1786).[2]
It occurs in hydrothermal veins within marble at the type locality in Modoc. It occurs associated with pyrite, sphalerite, wurtzite, galena, stibnite, orpiment, realgar, enargite, tetrahedrite, zinkenite, jordanite, bournonite, , boulangerite, jamesonite and sartorite at Madoc.[3]
In addition to the type locality, it has been reported from the Brobdingnag mine, near Silverton, Colorado; the Jas Roux deposit in Hautes-Alpes, France; from various marble quarries near Seravezza, Tuscany, Italy; a marble quarry in Valais, Switzerland and from Khaydarkan, Fergana Valley, Alai Mountains, Kyrgyzstan.[2][3]
References[]
- ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
- ^ a b c "Guettardite". mindat.org. Hudson Institute of Mineralogy. Retrieved October 10, 2020.
- ^ a b c Handbook of Mineralogy
- ^ Webmineral data
External links[]
- Discovery of guettardite in French
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- Sulfosalt minerals
- Lead minerals
- Monoclinic minerals
- Minerals in space group 14
- Sulfide mineral stubs