Tumbled selenite specimens are smooth, polished pieces of a transparent to translucent variety of gypsum, with the chemical formula CaSO₄·2H₂O (calcium sulfate dihydrate). These pieces retain the mineral’s fibrous structure and pearly luster, making them excellent examples of naturally formed evaporite minerals.
Features:
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Composition: Made of calcium sulfate with two water molecules per unit, selenite forms through the evaporation of mineral-rich water in sedimentary environments.
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Appearance: Typically colorless to white, with a silky or pearly sheen. The fibrous internal structure can produce a soft glow or chatoyancy under light.
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Formation: Occurs in clay beds, salt flats, and other evaporite settings where water slowly evaporates, leaving behind concentrated mineral layers.
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Physical Properties: Soft (Mohs hardness of 2), easily scratched, and sensitive to water. These specimens should be kept dry to maintain their integrity.
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Educational Value: Ideal for teaching mineral softness, crystal structure, and the geologic processes that form sedimentary minerals.
Tumbled selenite pieces are excellent for classroom use, geology collections, or anyone interested in the natural processes that shape Earth’s surface.
