Natural Yellow Optical Calcite Iceland Spar 97g

A chunky, blocky optical calcite rhomb in a pale straw-yellow tone, with a bright rainbow flash catching the light across its upper face. The crystal has good depth and translucency, allowing light to travel well into the body, with only faint internal cleavage lines visible throughout.

Optical calcite, also known as Iceland spar, is calcite crystallized into large, gem-clear cleavage blocks. It takes its 'optical' name from strong birefringence, light entering the crystal is split into two separate rays, so any line or image viewed through a clean section appears doubled. This effect made Iceland spar historically valuable for studying polarized light and building early optical instruments. Sourced from China and completely untreated. A solid, satisfying specimen for a mineral shelf or for demonstrating the double-refraction effect.

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