|
Lepidolite |
Chemical Formula |
KLi2Al(Al,Si)3O10(F,OH)2 |
Species |
Silicates |
Crystal System |
Monoclinic |
Mohs Scale |
2-3 |
Specific Gravity |
3.11 |
Color |
Pink, purple, rose-red, Purple-gray, yellowish, white, colorless |
Streak |
White |
Luster |
Sub-Vitreous, Resinous, Greasy, Pearly |
Refractive Index |
nα=1.525–1.548, nβ=1.551–1.58, nγ=1.554–1.586 |
Diaphaneity |
Transparent, Translucent |
Cleavage |
Perfect perfect |
Fracture |
Micaceous |
Crystal Habit:Tabular to prismatic pseudohexagonal crystals, scaly aggregates and massive |
Geological Setting:May be found in aplites associated with granite pegmatite. rarely found in hydrothermal veins and extremely rarely in granite contact zones. |
Lepidolite (KLi
2Al(Al,Si)
3O
10(F,OH)
2 is a lilac-gray or rose-colored polylithionite-trilithionite series, a phyllosilicate mineral series of the mica group that is a secondary source of lithium. 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.