Natural White Optical Calcite Iceland Spar 167g

This nearly cube-like optical calcite rhomb is clear to faintly milky throughout, with a small but bright rainbow flash visible along its right-hand cleavage face. A scattering of tiny dark mineral specks sits within the body, along with fine internal fracture lines typical of natural calcite cleavage.

Optical calcite, also known as Iceland spar, is calcium carbonate that grows in large, glass-clear cleavage blocks. The name 'optical' refers to its pronounced birefringence, light passing through the crystal is split into two rays, causing anything viewed through a clean section to appear doubled. This effect made Iceland spar historically significant for early optical science, including the development of polarizing microscopes. This piece comes from China and is completely untreated. It makes an interesting mineral specimen for demonstrating birefringence firsthand, or simply as a display piece.

Natural white optical calcite (Iceland spar), China - sold as a single piece.