Alabaster is a name applied to varieties of two distinct minerals: gypsum (a hydrous sulfate of calcium) and calcite (a carbonate of calcium). The first is the alabaster of the present day; the second is the alabaster of the ancients. Both are easily shaped, with an attractive appearance, and have been used for making a variety of artworks and objects, especially small carvings.


The two kinds are distinguished from one another readily, because of differences in their relative hardness. The gypsum kind is so soft it can be scratched with a fingernail (Mohs hardness 1.5 to 2), while the calcite kind is too hard to be scratched in this way (Mohs hardness 3).


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