mineral

Selenite (gypsum)

Gypsum, CaSO₄·2H₂O; likely a fibrous or cleavage fragment

AI-generated identification · may be incorrect

White to colorless, pearly to silky luster, with strong lengthwise striations; Mohs hardness 2 and very easily scratched by a fingernail. Gypsum is monoclinic and has excellent cleavage; the photo alone cannot confirm the exact variety or specific gravity.

Identified September 25, 2026More mineral →

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Physical properties

Formation & geological history

Forms when calcium-sulfate-rich water evaporates, and also in sedimentary beds and hydrothermal settings. Gypsum deposits occur in many geological ages; the specimen’s age cannot be determined visually.

Uses & applications

Used to make plaster, drywall, and cement; clear selenite is collected and sometimes carved into decorative objects.

Geological facts

Gypsum contains water within its crystal structure and is soft enough to be scratched with a fingernail.

Field identification & locations

The pale color and elongated, striated shape are consistent with gypsum, but a simple scratch test (fingernail) and lack of fizz in dilute acid help distinguish it from harder lookalikes. Gypsum is widespread; Afghanistan’s geology makes it plausible regionally, though the exact locality is unverified.