Blue Calcite Stones
Blue Calcite Rough Crystals
Blue calcite crystals with subtle but distinctive colour. With calcite being such a soft mineral stones tend to be stabilised which gives them a slightly shiny appearance. In certain light these blue calcite crystals look as if they may be slightly wet.
Calcite is made up primarily of calcium carbonate which is one of the most useful and versatile materials on the planet. One of the most familiar forms of calcium carbonate is blackboard chalk which is known to have been used for more than 10,000 years.
In its purest form the mineral calcite is white but the presence of various impurities causes a wide variety of colours including shades of red, blue, purple green, brown and black to name just a few. Stones can be transparent to opaque and lustre varies from vitreous to dull.
Colourless transparent calcite is widely used for optical instruments because some crystals display birefringence also known as double refraction. With this optical phenomenon certain light (unpolarized) travels through the crystal at different speeds and in different directions. The result is that one of the rays is bent at an angle or "refracted" whilst the other remains unchanged. To see this in action half fill a glass with water and stand a pencil or straw in the glass. At the very point where the object enters the water it appears to be misaligned. This is caused by refraction of light. The light only bends at the boundary so just where the water starts. Once in the water light continues to travel in a straight line. When refraction of light is viewed through the colourless transparent calcite crystal known as Iceland spar or optical calcite it causes "double vision".
These rough blue calcite crystals look great when placed together as a group but may be purchased individually. Price varies according to weight but unfortunately these nine stones are the only pieces we currently have available. We will be receiving more stock in due course but for the time being these are the last nine stones.