Selenite

The mineralogy is simple and well-characterised. Gypsum (CaSO4·2H2O) crystallises in the monoclinic system; the satin-spar variety used for most selenite wands is fibrous gypsum and the desert-rose variety is rosette-shaped. Hardness 2 on the Mohs scale means it scratches with a fingernail; solubility in water (~2.4 g/L at 20°C, rising at higher temperatures) is the practical reason it must be kept dry. The largest known crystals occur in the Naica mine in Chihuahua, Mexico — individual selenite beams up to 11 metres long, formed by 500,000 years of hydrothermal circulation at ~58°C (García-Ruiz et al., *Geology*, 2007). In modern crystal-healing practice, codified by Melody's *Love Is in the Earth* (1991) and Judy Hall's *The Crystal Bible* (2003), selenite is assigned to the crown chakra and used as a "cleansing" stone for other crystals — typically as a flat plate on which other stones are placed overnight. This use is contemporary (post-1990) rather than historical. The translucent silvery sheen is genuinely striking and the optical effect alone explains much of the modern appeal.

Gypsum has been quarried and used since prehistory — ancient Egyptian alabaster vessels and architectural elements are mostly fine-grained gypsum. The mineralogical name *selenite* was coined by Johan Gottschalk Wallerius (1709–1785), Swedish mineralogist and a founder of agricultural chemistry, in *Mineralogia, eller Mineralriket* (1747). The world's most spectacular selenite crystals are in the Cueva de los Cristales (Cave of the Crystals) at the Naica Mine in Chihuahua, Mexico, discovered in April 2000 — individual crystals reach 11 metres in length and an estimated 12 tonnes, formed by 500,000 years of mineral-rich water circulation in a stable 58°C environment (García-Ruiz, Villasuso, Ayora et al., *Geology*, 2007). Other major commercial sources are Morocco (Atlas Mountains), Brazil, and the US (notably Oklahoma and New Mexico). In modern crystal-healing tradition selenite was popularised as a cleansing tool by Melody's *Love Is in the Earth* (1991) and codified in Judy Hall's *The Crystal Bible* (2003). The specific claim that selenite "cleanses other crystals" is contemporary New Age rather than historical — no pre-1990 source assigns this function.

Care matters more than usual: Mohs hardness 2 means selenite scratches easily and is water-soluble (it slowly dissolves in liquid water, since gypsum is the basis of plaster of Paris). Never wash it, never leave it in a humid bathroom, and handle with care since fibres can flake. The Gemmological Institute of America's *Gem Reference Guide* gives the standard buyer caveats. Buy from a dealer who states the country of origin (Moroccan and Brazilian material are the most common). For the metaphysical-practice use, Judy Hall's *The Crystal Bible* (2003) gives the standard conventions. Treat the "cleanses other crystals" claim as a useful organising practice (a designated tray on which you set your other stones) rather than as documented pharmacology — the ritual structure is what gives it value. Cleanse selenite with moonlight, sound, or smoke; never with water or salt.