Bicchulite , Gehlenite Locality: Fuka mine, Bitchu-cho (Bicchu-cho), Takahashi , Okayama Prefecture , Chugoku Region , Honshu Island , Japan ( Locality at mindat.org ) Size: 8.5 x 7.3 x 3.9 cm. Bicchulite is a very rare calcium silicate and this very rich and showy specimen is from the Type Locality - the Fuka Mine of Japan. Sharp, gray, rectangular crystals to 4 mm of bicchulite pseudomorphs after gehlenite crystals richly cover the quartz-rich matrix on this specimen. Gehlenite is also a very rare calcium silicate. The Fuka Mine recovered high grade calcite for the toothpaste industry and is noted for interesting high temperature boron species. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Bicchulite
A calcium-aluminium silicate hydrate related to gehlenite, first recognized from hydrothermal syntheses and later found in Japanese mines.
Intro adapted from Wikipedia (CC BY-SA).
Bicchulite is an IMA-recognized mineral species in the silicate class, with the chemical formula Ca₂Al₂SiO₆(OH)₂.
It crystallizes in the cubic crystal system (space group I-43m). It is a member of the Cancrinite-sodalite, Sodalite structural group.
Key properties: Mohs hardness 2.5; specific gravity 2.813; Powdery, earthy luster.
IMA symbol Bch, IMA status: approved, named in 1973.
Found in skarns in limestones, formed through alteration of gehlenite subjected to later retrograde hydration reactions.
It is found associated with Vesuvianite, hydrogrossular, gehlenite, melilite, calcite.
The name refers to Bicchu, the town encompassing the Japanese type locality.