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Lepidolite var. ball-peen

#37795

Lepidolite var. ball-peen

#37795
Availability
Sold
Size
11 x 7 x 4 cm - Cabinet 
Formula
K(Li,Al)3(Si,Al)4O10(F,OH)2 (RRUFF)
Locality
Bennett quarry, Buckfield, Oxford Co., Maine, United States

Lilac "Lepidolite" forming rounded crystals. Lepidolite is a lithium rich mica falling withing the solid solution of polylithionite - trilithionite. According to Dr. David London, the lilac or purple color is not due to the presence of lithium but due to the presence of minor manganese. Lepidolite is found chiefly in pegmaties but not exclusive to pegmatites.

"Lepidolite" was actually discredited as a unique mineral species. It is rather a "catch-all" name describing purple or lilac colored Muscovites belonging to the solid solution group of Polylithionite - Trilithionite, which are lithium rich micas. Lepidolite is often found in LCT (lithium - cesium - tantalum) pegmatites and can often be enriched in rubidium.

This particular habit of Lepidolite is often described as "ball-peen" Lepidolite for its similarity to the ball-peen hammer. David London describes this habit in his book "Pegmatites" and again sites differential or rapid growth in the constantly evolving chemical environment. 

Lepidolite

Formula
K(Li,Al)3(Si,Al)4O10(F,OH)2 
Crystal System
Monoclinic 
Crystal Habit
Platy, Foliated, Massive 
Cleavage
Perfect, None, None 
Luster
Vitreous - Pearly 
Color
colorless, gray white, lilac, yellowish, white 
Streak
white 
Class
Monoclinic 
Fracture
Uneven 
Hardness
2.5-3 

Data courtesy of Webmineral.

Collection
Art Smith Collection

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