Minerals · common
Selenite
Selenite is a crystalline form of gypsum known for its transparency and moon-like glow. The Cave of Crystals in Mexico contains selenite crystals up to 12 meters long.
Also known as: gypsum crystal, moon stone, cleansing crystal.
Selenite properties at a glance
| Type | Minerals |
|---|---|
| Chemical formula | CaSO4·2H2O |
| Mohs hardness | 2 |
| Crystal system | monoclinic |
| Luster | vitreous |
| Streak | White |
| Cleavage | Perfect |
| Fracture | Fibrous |
| Specific gravity | 2.3 |
| Transparency | transparent |
| Common colors | Colorless, White, Peach, Gray |
| Rarity | common |
Geology & background
Forms through evaporation of saline water in sedimentary environments, creating crystals from gypsum.
Used by ancient Greeks for windows due to its transparency; the name 'selenite' was given by the Greeks.
How to identify Selenite
- Check whether the specimen's color and texture match typical Selenite examples.
- Photograph a fresh surface in natural light and avoid shadows, glare, or wet surfaces.
- Use hardness, streak, luster, grain size, and locality together; no single trait is enough for every specimen.
Full Selenite identification guide: checklist, home tests and look-alikes →
Selenite vs similar stones
Not sure it isn't something else? Side-by-side comparisons with the stones most often confused with Selenite.
Where Selenite is found
Selenite is reported from multiple localities or geological settings. Exact locality should be verified from specimen provenance, maps, or field notes.
How much is Selenite worth?
| Entry-level specimen | $5 |
|---|---|
| Typical collector specimen | $20 |
| Premium specimen | $150+ |
Value depends on size, condition, color, crystal quality, locality, rarity, preparation, and provenance. Treat this as educational guidance, not an appraisal.
Common uses
- Decorative objects
- Spiritual practices
- Plaster production
Interesting facts
- Named after Selene, Greek goddess of the moon
- Giant crystals in Mexico's Cave of Crystals took 500,000 years to form
- Soft enough to scratch with a fingernail
Care & safety
Treat Selenite as a collector specimen unless hardness, cleavage, and fracture are confirmed.
Avoid inhaling dust. Do not cut, grind, or polish unknown specimens without eye protection and a properly rated respirator.
Selenite FAQ
What is Selenite?
Selenite is a crystalline form of gypsum known for its transparency and moon-like glow. The Cave of Crystals in Mexico contains selenite crystals up to 12 meters long.
How much is Selenite worth?
Entry-level Selenite specimens sell for around $5, a typical collector specimen for about $20, and premium pieces for $150 or more. Value depends on size, condition, color, crystal quality, locality, rarity, preparation, and provenance. Treat this as educational guidance, not an appraisal.
How hard is Selenite?
Selenite has a Mohs hardness of 2. A fingernail (Mohs 2.5) scratches it easily.
Where is Selenite found?
Notable sources of Selenite include Mexico, Morocco, USA, Australia, and Greece. Forms through evaporation of saline water in sedimentary environments, creating crystals from gypsum..
What is Selenite used for?
Selenite is used for decorative objects, spiritual practices, and plaster production.
