Lepidolite, KLi2Al(F,OH)2(Si4O10) (Hydrous Potassium Lithium Aluminium Silicate), has Muscovite structure with Li 1+ ions replacing some of the Al 3+. It is distinguished 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: A square block of Lepidolite showing extensive crystallisation. Closer examination shows many crystalline flakes and scales. A very distinct pink-purple colouration enhanced by a waxy luster.

Location: Bikita, Zimbabwe.