Labradorite
Labradorite was named after peninsula of Labrador in Canada, where it was first found. It shows labradorescence - a shiller effect in lustrous metallic tints, often blue and green, and sometimes the complete spectrum. This effect is caused by interference of light from lattice distortions resulting from alternating microscopic exsolution lamellae of high- and low-calcium plagioclase phases.
| General Information | ||||||||||
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| A variety or type of: | Anorthite, which is a variety of Feldspar | |||||||||
| Other Names/Trade Names: | Spectrolite - Trade name for a Labradorite from Finland that shows the spectral colours especially effectively. | |||||||||
| Chemical Formula |
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| Physical Properties of Labradorite | ||||||||||
| Mohs Hardness | 6 to 6.5, Blue Chart Gem Identification (2010) More from other references | |||||||||
| Specific Gravity | 2.69 to 2.72, Blue Chart Gem Identification (2010) More from other references | |||||||||
| Tenacity | Brittle, Gems, Sixth Edition (2006) | |||||||||
| Cleavage Quality | Perfect, Gemmological Tables (2004) More from other references | |||||||||
| Fracture | Uneven, Gems, Sixth Edition (2006) | |||||||||
| Refractive Index | 1.554 to 1.573, Blue Chart Gem Identification (2010) More from other references | |||||||||
| Optical Character | Biaxial/+, Blue Chart Gem Identification (2010) More from other references | |||||||||
| Birefringence | 0.007 to 0.011, Blue Chart Gem Identification (2010) More from other references | |||||||||
| Pleochroism | From the Congo, red stones show weak pleochroism whilst greenstones have distinct greenish yellow to bluish green pleochroism, Gems, Sixth Edition (2006) | |||||||||
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