Sampleite
| Sampleite | |
|---|---|
 | |
| General | |
| Category | Phosphate minerals |
| Formula (repeating unit) | NaCaCu5(PO4)4Cl•5(H2O) |
| Strunz classification | 08.DG.05 |
| Crystal system | Orthorhombic |
| Space group | Orthorhombic (2/m 2/m 2/m) dipyramidal |
| Unit cell | a = 9.7 Å, b = 38.4 Å, c = 9.65 Å; β = 90.07°; Z = 8 |
| Identification | |
| Formula mass | 875.95 g |
| Color | Light blue to blue-green |
| Crystal habit | Aggregates, lath, rosette |
| Cleavage | Perfect on {010}; good on {100} and {001} |
| Mohs scale hardness | 4 |
| Luster | Pearly |
| Streak | Light Blue |
| Diaphaneity | Transparent |
| Specific gravity | 3.2 |
| Optical properties | Biaxial (-) |
| Refractive index | nα = 1.629 nβ = 1.677 nγ = 1.679 |
| Birefringence | δ = 0.050 |
| Pleochroism | X = deep blue, blue-green; Y = light blue, turquoise blue; Z = turquoise-blue, colorless |
| 2V angle | Measured: 5° to 23° |
| References | [1][2][3] |
Sampleite has a general formula of NaCaCu5(PO4)4Cl•5(H2O).[3] It was first described in 1942 for an occurrence in Chuquicamata, Chile and was named after Mat Sample, a mine superintendent for the Chile Exploration Company.[2]
Sampleite is orthorhombic, which means crystallographically, it contains 3 unequal axes with angles that are 90°. It belongs to the space group 2/m.[4] In a thin section it has a high surface relief and will have sharp boundaries with the surrounding medium. Sampleite is anisotropic and has visible pleochroism and birefringence.
It is characteristically found in earthy crusts in a highly sericitized rock and is present in highly oxidized conditions near the surface. When it occurs as micaceous rosettes and aggregates it can be associated with dendrites of manganese and iron oxides. Sampleite appears to be the most recent mineral deposited with the exception of gypsum.[5] [6]
External links
Media related to Sampleite at Wikimedia Commons
References
- ^ Handbook of Mineralogy
- ^ a b Mindat.org
- ^ a b Webmineral data
- ^ Campbell, T.J., Rapp, G.R., Roberts, W.L. (1990) Encyclopedia of Minerals (2nd Edition) 753 p. Library of Congress Cataloging, Washington D.C.
- ^ Hulbert, C.S. "Sampleite A New Mineral." http://www.minsocam.org/ammin/AM27/AM27_586.pdf. Retrieved 2010-11-11
- ^ "Sampleite Mineraology." http://www.wolframalpha.com/entities/minerals/sampleite/fx/0q/75/. Retrieved 2010-11-28
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