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Gypsum

Chemical Formula

CaSO4.2H2O

Chemical Class

Sulfates

Properties

It is a mineral with very low hardness, as it can be scratched with one´s nail. Usually translucent, there are transparent (selenite) and opaque varieties, forming beautiful prismatic and round tabular crystals (desert rose - formed in desertic plains from rare rain water evaporation).

Origin

Gypsum, Willow Creek Alberta, Canada

Curiosities

Gypsum can form more than 10-meter long crystals. It was found in a cave in Mexico. It is the most common sulphate in earth´s crust, and it is usually formed in marine evaporation lagoons (evaporites).

Use

Gypsum is used especially in plaster manufacturing, but is also used as fertilizer. A finely grained massive variety (alabaster) is used in sculpture manufacturing.

Source: MM Gerdau - Museu das Minas e do Metal -

ABC of mining

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