Calcite Laki Bulgaria

Calcite from the Laki mine in Bulgaria (year 2001).

Chemical formula: CaCO₃ (calcium carbonate). Hardness: 3 on the Mohs scale. Density: 2.6-2.8.

Stone dimensions: L: 150mm x W: 120mm x H : 70mm.

Weight: 1240g.

A few tips to help you identify Calcite:

• Hardness: On the Mohs scale, calcite has a hardness of 3, which means that it can be scratched by a steel knife but not by a fingernail.
• Streak: Calcite's streak (the colour of its powder) is generally white, regardless of the colour of the specimen.
• Acid Reaction: One of the most distinctive methods of identifying calcite is its effervescent reaction to dilute hydrochloric acid (HCl), even when cold. Calcite dissolves in the acid and produces bubbles of carbon dioxide (CO₂).

Cleaning

lukewarm water (washing-up liquid), soft bristle brush or toothbrush. Possibly to remove dust particles in the crevices, a jet of compressed air may be useful: use a compressed air canister (like those used to clean computer keyboards).