Austinite
Austinite is a member of the adelite-descloizite group, adelite subgroup, the zinc (Zn) end member of the copper-Zn series with conichalcite. It is the zinc analogue of cobaltaustinite and nickelaustinite. At one time “brickerite” was thought to be a different species, but it is now considered to be identical to austinite. Austinite is named in honour of Austin Flint Rogers (1877–1957), American mineralogist from Stanford University, California, US.
| Austinite | |
|---|---|
Austinite from the Ojuela Mine, Mexico | |
| General | |
| Category | Arsenate minerals |
| Formula (repeating unit) | CaZnAsO4(OH) |
| IMA symbol | Aus |
| Strunz classification | 8.BH.35 |
| Dana classification | 41.5.1.3 |
| Crystal system | Orthorhombic |
| Crystal class | Disphenoidal (222) H-M symbol: (2 2 2) |
| Space group | P212121 |
| Unit cell | a = 7.43, b = 9.00 c = 5.90 [Å], Z = 4 |
| Identification | |
| Formula mass | 261.38 g/mol |
| Color | Colourless, white to pale yellowish-white or bright green, colourless in transmitted light |
| Crystal habit | Well developed orthorhombic crystals of bladed or acicular habit elongated parallel to the c axis, sometimes with sceptre-like terminations, also radially fibrous crusts and nodules. Common forms are {110}, {111}, {1–11}, {010} and {011}. |
| Twinning | Left- and right-handed individuals joined on {100}, with {010} and {001} coincident. |
| Cleavage | Good in two directions parallel to the prism faces {110} |
| Tenacity | Brittle |
| Mohs scale hardness | 4 to 4.5 |
| Luster | Subadamantine to silky in fibrous aggregates |
| Streak | White |
| Diaphaneity | Translucent to transparent |
| Specific gravity | 4.12 |
| Optical properties | Biaxial (+) |
| Refractive index | nα = 1.759, nβ = 1.763, nγ = 1.783, |
| Birefringence | 0.024 |
| 2V angle | 47° |
| Dispersion | r > v weak |
| Solubility | Easily soluble in cold dilute HCl |
| Other characteristics | Non-radioactive. Some austinite fluoresces green under SWUV. |
| References | |
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.