Fluorite on Quartz

This rather spectacular octahedral Fluorite, pierced by two parallel smoky Quartz crystals, is from the Akchatau mine in Karagandy Province, Kazakhstan.  The greisen-hosed deposit was discovered in 1936 and has been mined since 1941.  The mine exploits over 300 tungsten mineralised greisen veins, zones within the granite which have been altered by migrating super-heated gas and fluid-flow during crystallisation and solidification.  Two complete and four part-complete octahedron faces form this large miniature, with roughly stepped faces of opaque, intensely deep blackberry-purple Fluorite, so dark as to appear almost black.  Embedded within the base of the crystal where the faces are incomplete, are two hexagonal Quartz crystals measuring 4.5 and 4.2 cm long.  The longer crystal is dark-smoky and the shorter, light smoky-grey, both of whose terminations peep out from one side of the Fluorite octahedron.  A splendid and unusual octahedral fluorite with Quartz from Kazakhstan.