Selenite
Gypsum
What is Selenite?
Selenite is a variety of the mineral gypsum, which is a soft sulfate mineral composed of calcium sulfate dihydrate. It is known for its large, transparent crystals, often found in arid environments and caves. Selenite crystals can form in various habits, including tabular, prismatic, and fibrous forms. The name "Selenite" comes from the Greek word for "moon," reflecting its pearly luster and translucent appearance. It is often used for decorative purposes and in crystal healing practices.
Optical Properties
- Refractive Index
- 1.520-1.530
- Birefringence
- 0.009
- Pleochroism
- None
- Optical Character
- Biaxial positive
Discover Values
Market Value Factors
Pricing varies for every rock and mineral, so use these universal factors to gauge Selenite before comparing listings or appraisals.
Size & Weight
Larger, intact specimens usually command higher prices.
Rarity & Demand
Scarce material or popular varieties sell at a premium.
Condition & Finish
Chips, repairs, and heavy wear lower value; clean prep helps.
Treatment & Provenance
Untreated specimens with documented locality are prized.
Where to Find Selenite
RockHoundR, the free-to-download rockhounding map from the Ruby Glint team, shows where collectors find selenite in the US, with land-access notes for BLM land and national forests. Collecting is banned in national parks.
See where to find seleniteAlways check the local rules and get the landowner's permission before you collect.
Quick Facts
Physical Properties
- Color
- Colorless, white, gray, yellow, brown, orange, and rarely green or blue
- Hardness (Mohs)
- 1.5-2
- Rock tumbling
- Not recommended
- Density
- 2.32 g/cm³
- Luster
- Pearly to vitreous
- Crystal System
- Monoclinic
Chemical Properties
- Chemical Formula
- CaSO₄·2H₂O
- Elements
- Ca, S, O, H
Also Known As
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Selenite FAQs
How do I identify Selenite?
Selenite can be identified by its hardness of 1.5-2 on the Mohs scale, Colorless color, Pearly to vitreous luster, Monoclinic crystal system. Look for these key characteristics when examining specimens.
What color is Selenite?
Selenite typically appears in Colorless, white, gray, yellow, brown, orange, and rarely green or blue. Color can vary depending on impurities and formation conditions.
How hard is Selenite?
Selenite has a hardness of 1.5-2 on the Mohs scale. This makes it a soft mineral that can be scratched easily.