Staurolite
Brazil
0.72 carats
© Rarestone.com
Staurolite forms characteristic monoclinic, pseudo-orthorhombic prismatic, reddish brown crystals, often forming 60° twins. The crystals are mostly translucent, rarely transparent. Staurolite shows distinct pleochroism - colourless - yellow - reddish brown.
Rouch material to facet brilliant gems is very rare.
Staurolite Gemstones by Colour
This table shows the variety of hues this gemstone can be found in. Click on a photo for more information.
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| General Information | ||||||||||||||||||||||
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| Chemical Formula |
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| Physical Properties of Staurolite | ||||||||||||||||||||||
| Mohs Hardness | 7 to 7.5, Blue Chart Gem Identification (2010) More from other references | |||||||||||||||||||||
| Specific Gravity | 3.7 to 3.8, Gemstones of the world (2001) More from other references | |||||||||||||||||||||
| Cleavage Quality | Distinct, Gemmological Tables (2004) More from other references | |||||||||||||||||||||
| Fracture | Sub-Conchoidal, Gemstones (2009) | |||||||||||||||||||||
| Optical Properties of Staurolite | ||||||||||||||||||||||
| Refractive Index | 1.736 to 1.762, Blue Chart Gem Identification (2010) More from other references | |||||||||||||||||||||
| Optical Character | Biaxial/+, Blue Chart Gem Identification (2010) More from other references | |||||||||||||||||||||
| Birefringence | 0.010 to 0.015, Blue Chart Gem Identification (2010) More from other references | |||||||||||||||||||||
| Pleochroism | Distinct: light yellow - yellowish red - dark red, Blue Chart Gem Identification (2010) More from other references | |||||||||||||||||||||
| Dispersion | Nil, Gemstones (2009) | |||||||||||||||||||||
| Colour | ||||||||||||||||||||||
| Colour (General) | Reddish-brown, black., Gemstones of the world (2001) More from other references | |||||||||||||||||||||
| Causes of Colour | Brown, Fe2+ in tetrahedral coordination. Blue, Co2+ in tetrahedral coordination, Pragmatic Spectroscopy For Gemologists (2011) | |||||||||||||||||||||
| Transparency | Transparent, Blue Chart Gem Identification (2010) More from other references | |||||||||||||||||||||
| Lustre | Vitreous, Gemstones of the world (2001) More from other references | |||||||||||||||||||||
| Crystallography of Staurolite | ||||||||||||||||||||||
| Crystal System | Monoclinic, Gemstones of the world (2001) More from other references | |||||||||||||||||||||
| Habit | Pseudo-orthorhombic prismatic, Gems, Sixth Edition (2006) More from other references | |||||||||||||||||||||
| Geological Environment | ||||||||||||||||||||||
| Where found: | Staurolite occurs most commonly in schists and gneisses., Gems, Sixth Edition (2006) | |||||||||||||||||||||
| Further Information | ||||||||||||||||||||||
| Mineral information: | Staurolite information at mindat.org | |||||||||||||||||||||
| Significant Gem Localities | ||||||||||||||||||||||
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