Selenite vs Satin Spar

What is the difference between these two crystals and should you even care?

Recently, crystal retailers have started labelling the crystal commonly known as 'Selenite' a little bit differently and it has sparked some complaints from customers. Let me introduce you to Satin Spar [pronounced like the material].

While both Satin Spar and Selenite are sulfur-based minerals which come from the Gypsum family, they have a few visual and geological differences. It is important to note that they have long been listed as different crystals but as they both come from Gypsum, retailers have been labelling them as the same crystal out of convenience and partially misinformation presented to them by their wholesaler.

Let's start with the question "why do the names matter?"

How I like to think about it is; Rose Quartz and Amethyst are both members of the Quartz family. If I were to list Rose Quartz as an 'Amethyst Specimen' my customers would probably be pretty confused as it is fairly well known that an Amethyst is found in shades of purple, not pink. Likewise, if I was selling an Amethyst crystal as 'Purple Quartz' customers would likely assume that it is a dyed quartz and not a natural stone.

Selenite Knife Carving

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What is Gypsum?

Gypsum is an evaporite mineral most commonly found in layered sedimentary deposits in association with halite, anhydrite, sulfur, calcite and dolomite. Gypsum is very similar to Anhydrite, the chemical difference being that gypsum contains two waters and anhydrite is without water. Gypsum however, is the most common of the sulfate minerals.

Uses for Gypsum actually include: manufacture of wallboard, cement, plaster of paris, soil conditioning, and a hardening retarder in portland cement. Varieties of gypsum known as "satin spar" and "selenite" are used for a variety of ornamental purposes; however, their low hardness limits their durability.

Selenite

This Gypsum variety is most often transparent and colourless

If selenite crystals show opacity or colour, it is caused by the presence of other minerals, sometimes in druse.

Satin Spar

This fibrous variety of Gypsum has a silky lustre and is referred to as satin spar; it is partially translucent and opalescent and is valued for ornaments and jewellery. Most often silky and fibrous; this mineral can exhibit some variation in colour depending on other minerals within it.

Desert Rose

Desert rose is the colloquial name given to rose-like formations

of gypsum. The rosette crystal habit tends to occur when the crystals form under arid sandy conditions, such as a shallow salt basin becoming evaporated. The crystals form a circular series of flat plates that give the rock a similar shape to a rose blossom.

The average size of rose rocks is anywhere from 1.3 cm to 10 cm in diameter. The largest recorded by the Oklahoma Geological Survey was 43 cm across and 25 cm high, weighing 57 kg.

Which of the Gypsum crystals are your favourite?

Let us know!

• Selenite
• Satin Spar
• Desert Rose