Large glowing green fluorite in octahedral form with second-generation fluorite cubes

A large, luminous green fluorite octahedron from Guilin, China, on the surface of which a second generation of smaller fluorite cubes has grown. A rare two-generation constellation of the same mineral.

Fluorite (CaF₂) crystallizes cubically and can occur in both cubes and octahedra. The octahedral form results from perfect cleavage in four directions. The cubic form is the direct cubic growth variant.

The presence of both habits on a single specimen documents a two-stage cavity genesis. First, the main octahedron formed under specific solution conditions, then a second phase with altered pressure and solution conditions favored the cubic habit.

The green color of the fluorite comes from traces of yttrium or rare earths. Guilin is known as a premium deposit for stepped fluorite structures; the South China karst region provides such specimens in high quality.