Selenite is a variety of gypsum with a distinctive crystalline structure. Gypsum is a very soft mineral made up of calcium sulphate dihydrate (dihydrate meaning two molecules of water). When dissolved in water calcium sulphate causes permanent hardness.
Gypsum is widely used as a fertiliser, for blackboard chalk and is the main constituent of plaster (and plaster of Paris). Selenite is crystallised gypsum.
Satin spar and selenite are not the same material. Satin spar features long fibrous crystals that are white and opaque. It usually has a distinctive silky or pearly lustre and is often incorrectly labelled as selenite.
Selenite forms translucent or transparent colourless crystals. This mineral is so soft that it can be scratched with a fingernail.
Although it can't be appreciated from our photos, this free-standing piece has a vitreous lustre. Minerals with a this kind of lustre reflect light in a similar way to glass.
Some of the crystal faces can be felt on the front but the back is completely smooth.
These formations are often known as fishtails because of their shape.
The name selenite originates from the Greek word for 'moon' and 'stone' or 'stone of the moon'. In Greek mythology Selene was the goddess of the moon.
In the metaphysical world selenite calms, soothes and relaxes on both a mental and physical level. It dispels negativity and radiates positive energy.
Submerging selenite in water for any length of time will cause irreparable damage to the crystals. To keep this mineral in tip top condition it should not be allowed to come into contact with moisture.