Rob Lavinsky, iRocks.com – CC-BY-SA-3.0 [CC-BY-SA-3.0], via Wikimedia Commons
Reddish granular or massive lepidolite is usually slabbed for ornamental purposes, such as ashtrays paperweights, and bookends. Faceted micas are virtually nonexistent because of the perfection of the cleavage and the variable hardness within crystals.
| Data | Value |
|---|---|
| Name | Lepidolite |
| Colors | Colorless: yellow, pink, purplish, white, grayish, reddish. |
| Crystallography | Monoclinic. Crystals tabular; also masses of plates, spheroidal masses. |
| Refractive Index | 1.525-1.587 |
| Luster | Pearly on cleavage. |
| Hardness | 2.5-4. |
| Fracture | Uneven, micaceous |
| Specific Gravity | 2.8-3.3 |
| Birefringence | 0.018-0.038. |
| Cleavage | Perfect and easy 1 direction |
| Stone Sizes | Large nodules from California are up to 6 inches or more across. Lepidolite, like the other micas, is rarely transparent enough to facet, and then it is so difficult to cut that few people ever attempt the feat! Facetable lepidolite does exist, notably from Brazil. |
| Luminescence | None. |
| Luminescence Present | No |
| Transparency | Translucent to transparent. |
| Absorption Spectrum | Absorption stronger in the plane of the cleavage. Not diagnostic. |
| Formula |
K(Li,AI)3(Si,AI)4O10(F,OH )2. |
| Optics |
a = 1.525-1.548; β = 1.551-1.585; γ = 1.554-1.587. Biaxial (–), 2V= 0-58°. |
| Optic Sign | Biaxial - |
LEPIDOLITE Mica family.
Optics: a = 1.525-1.548; β= 1.551-1.585; γ= 1.554-1.587.
Biaxial ( – ), 2V= 0-58°.
Occurrence: Almost exclusively in granite pegmatites; also in tin veins.
San Diego County California: Gunnison, Colorado; Black Hills. South Dakota; Wyoming; Arizona; New Mexico; New England, especially Maine.
Sweden; Germany: Finland; Czechoslovakia; USSR; Madagascar; Japan; Bikita, Zimbabwe. Brazil: fine pink and reddish crystals.
Comments: Reddish granular or massive lepidolite is usually slabbed for ornamental purposes, such as ashtrays paperweights, and bookends. Faceted micas are virtually nonexistent because of the perfection of the cleavage and the variable hardness within crystals.
Name: From the Greek lepis, (scale) because of the scaly nature of the massive material.
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