Mineral Species: Lepidolite

Chemical Formula: KLi2Al(F,OH)2(Si4O10)

Chemical Name: Hydrous Potassium Lithium Aluminium Silicate

Mineral Class: Phyllosilicate

Mineral Notes: Lepidolite has Muscovite structure with Li 1+ ions replacing some of the Al 3+. Like other micas, the mineral has a layered structure of aluminum silicate sheets weakly bonded together by layers of potassium ions. These potassium ion layers produce perfect cleavage. Lepidolite is distinguished from other micas by the pink colouration and is one of the most important sources of the metal Lithium. When added to glass it lowers thermal expansion and thus makes the glass less likely to shatter when heated. This is the basis of Pyrex glass. 

Description: An unusual botryoidal specimen of Lepidolite. The individual sheets are stacked on each other and curved, producing the semi-spherical clusters. The colour is strong and is a very attractive pink.

Location: Minas Gerais, Brazil.