Roscoelite

Name:
Roscoelite
Detailed information:

M Formula:	K2V4Al2Si6O20(OH)4
Properties:
A vanadium-bearing species of mica. Formula variable with V2O3 up to 28%. Occurs as minute scales with micaceous cleavage, dark green to brown in color, pearly luster, Mohs hardness 2.5, d 3.0.
Occurrence:
Colorado, California, Australia.
Use:
Source of vanadium.