Jeremejevite
Image: Robert M. Lavinsky (CC BY-SA 3.0)
Mineral NameJeremejevite
Chemical FormulaAl₆(BO₃)₅(F,OH)₃
Mohs Hardness6.5
Crystal Systemhexagonal
Lustervitreous
Streak Colorwhite
Cleavagepoor/indistinct on {1010}
Fractureconchoidal
Specific Gravity3.29
Colorslight blue, colorless, white, yellowish, brownish, violet
Transparencytransparent
Type LocalityErongo Mountain, Usakos and Omaruru Districts, Erongo Region, Namibia
Mineral GroupBorates
Usesgemstone, collector
Associated Mineralsquartz, tourmaline, albite, microcline, schorl, fluorite, apatite
Rarityvery-rare
Description
This image displays a superb, gemmy, and lustrous light blue jeremejevite crystal, approximately 6 mm in size, aesthetically set. It exhibits a hexagonal prismatic habit typical of the mineral.
Geological Context
Jeremejevite is a rare borate mineral typically found in granite pegmatites and contact metamorphic deposits. Its formation is associated with boron-rich fluids in these geological environments.
