Jeremejevite
Image: Fred Kruijen (CC BY-SA 3.0 nl)
Mineral NameJeremejevite
Chemical FormulaAl₆B₅O₁₅(F,OH)₃
Mohs Hardness6.5
Crystal Systemhexagonal
Lustervitreous
Streak Colorwhite
Cleavagepoor on {1010}
Fractureconchoidal
Specific Gravity3.29
Colorspale blue, white
Transparencytransparent
Type LocalityWannenköpfe, Ochtendung, Eifel region, Germany
Mineral GroupBorates
Usescollector, gemstone
Associated Mineralsquartz, feldspar, tourmaline, fluorite
Rarityrare
Description
A tiny, pale blue, spherical aggregate of radiating acicular crystals, resembling a fluffy ball, nestled within a cavity among larger, clear to translucent, brownish-white mineral grains.
Geological Context
Jeremejevite typically forms in granite pegmatites or metasomatic environments. In the Eifel region, it is found in cavities within volcanic ejecta, a rare occurrence for this mineral.
