Sampleite

Sampleite
General
Category Phosphate minerals
Formula
(repeating unit)		 NaCaCu5(PO4)4Cl•5(H2O)
Strunz classification 8.DG.05
Crystal system Monoclinic
Crystal class Prismatic (2/m)
(same H-M symbol)
Space group P21/n or P21/c
Unit cell a = 9.7 Å, b = 38.4 Å
c = 9.65 Å; β = 90.07°; Z = 4
Identification
Formula mass 875.95 g/mol
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 monoclinic. It belongs to the space group P21/n or P21/c.[4][5] 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.[6][7]

Media related to Sampleite at Wikimedia Commons

References

  1. ↑ Handbook of Mineralogy
  2. 1 2 Mindat.org
  3. 1 2 Webmineral data
  4. ↑ Mineralienatlas
  5. ↑ Campbell, T.J., Rapp, G.R., Roberts, W.L. (1990) Encyclopedia of Minerals (2nd Edition) 753 p. Library of Congress Cataloging, Washington D.C.
  6. ↑ Hulbert, C.S. "Sampleite A New Mineral." http://www.minsocam.org/ammin/AM27/AM27_586.pdf. Retrieved 2010-11-11
  7. ↑ "Sampleite Mineraology." http://www.wolframalpha.com/entities/minerals/sampleite/fx/0q/75/. Retrieved 2010-11-28
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