mineral
Satin Spar (often marketed as Selenite)
Gypsum (Calcium Sulfate Dihydrate) - CaSO4·2H2O
Hardness: 2 on Mohs scale (can be scratched by a fingernail). Color: White or colorless with an opalescent sheen. Luster: Vitreous to pearly/silky. Crystal structure: Monoclinic, typically fibrous in this form. Cleavage: Perfect in one direction.
- Hardness
- 2 on Mohs scale (can be scratched by a fingernail)
- Color
- White or colorless with an opalescent sheen
- Luster
- Vitreous to pearly/silky
Identified More mineral →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 2 on Mohs scale (can be scratched by a fingernail). Color: White or colorless with an opalescent sheen. Luster: Vitreous to pearly/silky. Crystal structure: Monoclinic, typically fibrous in this form. Cleavage: Perfect in one direction.
Formation & geological history
Formed as an evaporite mineral in sedimentary environments, typically where saline water evaporates in landlocked basins or lagoons. They range from recent formations to hundreds of millions of years old depending on the geological deposit.
Uses & applications
Used in the manufacture of drywall (plasterboard), cement, and plaster of Paris. In the decorative market, it is popular for carved lamps, 'towers,' and metaphysical items.
Geological facts
Satin spar is often mislabeled as 'Selenite' in the commercial market. While both are varieties of gypsum, true selenite is transparent and plate-like, while satin spar is fibrous and milky. It is one of the softest minerals in existence.
Field identification & locations
Identify in the field by its extreme softness (scratches with a fingernail) and silky, fibrous appearance. Commonly found in massive beds in locations like Morocco, Mexico (Naica), and the United States (Utah and New Mexico). Collectors should avoid getting it wet as it is slightly water-soluble.
More like this
Other mineral specimens
Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic
Nephrite Jade
Nephrite
Mineral/Rock
Banded Gneiss (River Rock/Pebble)
Gneiss (specifically a banded variety often found as a river rock)
Metamorphic Rock
![Green Apatite on Albite (Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]) — mineral](https://media.rockidentification.com/2391a63f-fb20-47d5-af9a-2035851eb32e-thumbnail.jpg)
Green Apatite on Albite
Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]
mineral
Epidote
Epidote - Ca2(Al2,Fe3+)3(SiO4)3(OH)
mineral