Bertrandite
Nevada, USA
21.60 carats
© Giovanni Scapin 2015
Bertrandite forms transparent, colourless to pale yellow crystals. Large and clean enough crystals suitable for faceting are rare.
Bertrandite often occurs as a pseudomorphic replacement of beryl.
| General Information | ||||||||||||||||||
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| Chemical Formula |
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| Physical Properties of Bertrandite | ||||||||||||||||||
| Mohs Hardness | 6 to 7, Handbook of mineralogy (2001) | |||||||||||||||||
| Specific Gravity | 2.59 to 2.60, Handbook of mineralogy (2001) | |||||||||||||||||
| Cleavage Quality | Perfect,Distinct, Handbook of mineralogy (2001) | |||||||||||||||||
| Optical Properties of Bertrandite | ||||||||||||||||||
| Refractive Index | 1.583 to 1.614, Handbook of mineralogy (2001) | |||||||||||||||||
| Optical Character | Biaxial/-, Handbook of mineralogy (2001) | |||||||||||||||||
| Dispersion | Weak, Handbook of mineralogy (2001) | |||||||||||||||||
| Colour | ||||||||||||||||||
| Colour (General) | Colorless to slightly yellow, Handbook of mineralogy (2001) | |||||||||||||||||
| Transparency | Transparent, Handbook of mineralogy (2001) | |||||||||||||||||
| Lustre | Vitreous,Pearly, Handbook of mineralogy (2001) | |||||||||||||||||
| Crystallography of Bertrandite | ||||||||||||||||||
| Crystal System | Orthorhombic, Handbook of mineralogy (2001) | |||||||||||||||||
| Habit | Crystals thin tabular, commonly prismatic to needlelike, to 5 cm; in radial aggregates., Handbook of mineralogy (2001) | |||||||||||||||||
| Geological Environment | ||||||||||||||||||
| Where found: | In fissures in granites and associated pegmatites and in miarolitic cavities in greisens; commonly an alteration product of beryl, more rarely as a primary mineral., Handbook of mineralogy (2001) | |||||||||||||||||
| Further Information | ||||||||||||||||||
| Mineral information: | Bertrandite information at mindat.org | |||||||||||||||||