Kentrolite Locality: Norrbotten working, Långban , Filipstad , Värmland , Sweden ( Locality at mindat.org ) Size: miniature, 3.4 x 2.4 x 1.2 cm Kentrolite on Braunite A specimen of massive braunite reich with sparkling microcrystalline kentrolite all over it - I am told this is a pretty good specimen for the price and richness, but they are micros and its black on black so its not the prettiest piece, I admit. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Kentrolite
Kentrolite is an IMA-recognized mineral species in the silicate class, with the chemical formula Pb₂Mn³⁺₂O₂(Si₂O₇).
It crystallizes in the orthorhombic crystal system (space group Pbcn).
Key properties: Mohs hardness 6; specific gravity 6.19; typically brown or black; Yellowish brown streak; Vitreous to submetallic, greasy, dull luster; optically biaxial.
IMA symbol Ken, grandfathered status — known before the IMA’s founding, named in 1881.
Found in a cavity in calcite in a metamorphosed stratiform zinc deposit (Franklin, New Jersey, USA); in veinlets cutting franklinite ore in bedded manganese deposits (Ushkatyn deposits, Kazakhstan).
It is found associated with Quartz, barite, apatite (\Chile"); braunite, richterite, barite (Lº angban, Sweden); calcite, willemite, franklinite (Franklin, New Jersey, USA); garnet.
Its name comes from the Greek for spike or thorn, for its prismatic habit.
Collections: Collector Favorites, Rare & Remarkable.