Judging quality
Satin spar shows a moving cat's-eye line down its length; true selenite plates are transparent enough to read through. Look for uncracked, undulled surfaces.
Gypsum
Selenite
A clear, satin or fibrous variety of gypsum that grows in blades, wands and — at Naica in Mexico — beams over ten metres long. Soft enough to scratch with a fingernail.
Care
Water dissolves it. Never wash selenite; dust with a dry brush only, and keep it off damp surfaces.
History & lore
The Cave of the Crystals at Naica, discovered in 2000, holds the largest natural crystals ever documented.
Cultural history, recorded as tradition rather than as medical or scientific claim.
Common questions about Selenite
- What is Selenite?
- A clear, satin or fibrous variety of gypsum that grows in blades, wands and — at Naica in Mexico — beams over ten metres long. Soft enough to scratch with a fingernail.
- How hard is Selenite and what is it made of?
- Selenite is a Gypsum-family mineral with the composition CaSO4·2H2O. It crystallizes in the monoclinic system and rates 2 on the Mohs hardness scale. It occurs in white, colorless, peach.
- Where does Selenite come from?
- Notable localities for Selenite include Morocco, Mexico (Naica), USA (Oklahoma).
- How do you tell good Selenite from filler?
- Satin spar shows a moving cat's-eye line down its length; true selenite plates are transparent enough to read through. Look for uncracked, undulled surfaces.
- How do you care for Selenite?
- Water dissolves it. Never wash selenite; dust with a dry brush only, and keep it off damp surfaces.
See it in person
Photographs only go so far
Both rooms are open six days a week, and there is always someone happy to pull pieces out of the case so you can compare them under the light.