This specimen consists of complex intergrown golden calcite crystals perched on a limestone matrix, from the Irving Materials Quarry in Anderson, Indiana. Under visible light this specimen possesses what is referred to as "the inner light," an apparent inner glow, due to internal reflection from within the crystal that contrasts against the surrounding golden color. As shown below, under mid wave UV, the calcite shows a beautiful pink-purple fluorescence. The size of the full specimen is 53 x 43 x 36 mm and the calcite crystal measures 28 x 26 x 24 mm.
In the photograph above, taken under mid wave UV (302 nm), the calcite shows a beautiful pink-purple fluorescent response.
Photograph of the same specimen taken under visible light. Note the internal glow, or "inner light," of the calcite crystals.