Lepidolite

Lepidolite is a lilac-gray or rose-colored member of the mica group with formula K(Li,Al,Rb)₃(Al,Si)₄O₁₀(F,OH)₂. It is a secondary source of lithium. It is a phyllosilicate mineral and a member of the polylithionite-trilithionite series.

It is associated with other lithium-bearing minerals like spodumene in pegmatite bodies. It is one of the major sources of the rare alkali metals rubidium and caesium. In 1861 Robert Bunsen and Gustav Kirchhoff extracted 150 kg of lepidolite and yielded a few grams of rubidium salts for analysis, and therefore discovered the new element rubidium.

It occurs in granite pegmatites, in some high-temperature quartz veins, greisens and granites. Associated minerals include quartz, feldspar, spodumene, amblygonite, tourmaline, columbite, cassiterite, topaz and beryl.

Notable occurrences include Brazil; Ural Mountains, Russia; California, United States; Tanco Mine, Bernic Lake, Manitoba, Canada; and Madagascar.

Yellow lepidolite from Itinga, Minas Gerais, Brazil. Size: 6.1 x 4.9 x 3.1 cm