Class: Sulphates
Group: Scheelite
Original description: ‘Scheelit’ von Leonhard, K. C., 1821. Scheelit — Handbuch der Oryktognosie, Heidelberg: 594—596 [
view in ‘Library’].
Type locality: Bispbergs, Säter, Dalarna, Sweden.
Type material: unknown.
Etymology: named after Swedish chemist Carl Wilhelm Scheele, who discovered tungsten.
Distribution: an important ore of tungsten, with many localities: Brazil: Minas Gerais; Canada; China; Germany: Altenberg and Schwarzenberg, Saxony; Italy: Piedmont; Mexico; Namibia; Russia; South Korea; Sweden: Dalarna; Vietnam (
Anthony et al., 2001—2005).
Chemistry
Ca(WO4)
Essential elements: oxygen (O), calcium (Ca), tungsten (W).
Crystal data
Crystallography: tetragonal — dipyramidal.
Crystal habit: crystals are typically pseudo-octahedral {011} or {112}, with modifying forms {001}, {013}, {121}, to 32 cm; commonly granular, massive.
Twinning: {110}, common, penetration and contact twins, composition plane {110} or {001} (
Anthony et al., 2001—2005).
Optical properties
Colour: colourless, white, grey, brown, pale yellow, yellow-orange, pale shades of orange, red, green; may be compositionally colour zoned (
Anthony et al., 2001—2005).
Diaphaneity: transparent to opaque (
Anthony et al., 2001—2005).
Lustre: vitreous to adamantine (
Anthony et al., 2001—2005).
Refractive index: 1.918—1.936 — anisotropic [uniaxial (+)] (
Lazzarelli, 2012).
Birefringence: 0.01—0.018.
Dispersion: 0.038.
Pleochroism: none.
Material from ‘Repository’