Wax coating on calcite

The blue calcite on the left (now in the collection of ) has been coating with a thin film of wax that gives it a smooth, liquid-looking surface.

Contrast it with the golden-brown calcite crystal edge on the right, photographed at the 2010 Victorian Gem and Mineral Show, with a bare, unaltered surface. The sides are smooth and the edges end in a crisp point, compared to the more rounded 'wet' look of the blue calcite.

Calcite is a soft mineral with a Moh's hardness score of 3. When large amounts of inexpensive pieces are shipped in a box, they tend to roll around and scratch each other, or get scratched by other stones. Surface scratches and imperfections make the crystals seem less clear than they really are. Therefore, suppliers often coat all of them with a layer of wax which fills the scratches and makes them look better. It also offers some protection.

Often, if the waxed stones are handled roughly or placed in running water for an extended period of time (eg, kept in a fish tank), the wax gets worn off, exposing a duller surface.

More expensive specimens may be boxed individually with padding, so wax coating is not neccesary.

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