Calcite

specimen number:
2072037

location:
Mexico

description:
A loose gem quality cleavage rhombohedron of calcite, the type often called Iceland spar. This shows excellent double refraction.

Calcite is a calcium carbonate mineral that occurs in a wide variety of crystal forms and geological environments, but one of its most famous varieties is Iceland spar, a clear and colorless form known for its exceptional optical properties. Iceland spar exhibits strong double refraction, meaning that light passing through the crystal is split into two separate rays, producing a doubled image when viewed through the mineral. This effect occurs because calcite has anisotropic optical properties, causing light to travel at different speeds depending on its direction within the crystal lattice. Iceland spar was historically used in optical experiments and instruments, including early polarizing devices, due to this pronounced birefringence.

Questions about this specimen?
Send an email or call us: 314-341-1811.