Petite Calcite Cube - Iceland Spar Optical Calcite Crystal - Clear Double Refraction Calcite

Set this little cube on a printed word and you will see the letters double. That is double refraction, the famous property of clear calcite known as Iceland spar. This petite optical calcite cube measures about 12 to 20 millimeters on each side.

It is a fun, hands-on specimen for kids and adults curious about science, a neat desk piece, and a classic addition to any mineral collection. It is sometimes sold as 'optical quartz', but it is calcite, a much softer mineral, so handle it gently and keep it away from harder stones.

About Iceland Spar

Iceland spar is transparent calcite, calcium carbonate. Light passing through it splits into two rays, so anything viewed through the crystal appears doubled. Calcite rates 3 on the Mohs scale and has perfect cleavage in three directions, which is why it naturally breaks into rhomb-shaped blocks.

Additional Details

• You receive 1 petite calcite cube.
• Approximate size: 12-19mm x 12-20mm x 12-19mm.
• Care: calcite is soft (Mohs 3) and cleaves easily; avoid drops and scratches.
• Stock photo. Clarity and shape vary.

Frequently Asked Questions

Why does calcite make words look double? Clear calcite has double refraction: it splits light into two rays, so you see two images through it.

Is Iceland spar quartz? No. It is sometimes called optical quartz, but Iceland spar is clear calcite, a different and softer mineral.