Jeremejevite Locality: Arandis , Swakopmund District, Erongo Region , Namibia ( Locality at mindat.org ) For rarity and sheer aesthetics, this is a stunning little thumb. The color, luster, and sheer beauty of the crystals speak for themselves. Note the size - it isn't a big thumbnail, but it is an elgant example of a very rare species (and blue is the classic color) 1.4 x 1.2 x 1.2 cm — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Jeremejevite
An aluminium borate with fluoride and hydroxyl — among the rarest facetable collector's gems.
Intro adapted from Wikipedia (CC BY-SA).
Jeremejevite is an IMA-recognized mineral species in the borate class, with the chemical formula Al₆(BO₃)₅F₃.
It crystallizes in the hexagonal crystal system (space group P6_3/m).
Key properties: Mohs hardness 6.5–7.5; specific gravity 3.29; Vitreous luster; refractive index 1.647; optically uniaxial.
IMA symbol Jer, grandfathered status — known before the IMA’s founding, named in 1883.
A rare late hydrothermal mineral formed in granitic pegmatites.
It is found associated with Albite, tourmaline, quartz, gypsum (Cape Cross, Namibia).
The mineral was named to honor Pavel Vladimirovich Eremeev (Jeremejev, German) (1830–1899), Russian mineralogist and crystallographer, who first recognized this species.