RocksdayMuscovite vs Selenite
To tell Muscovite from Selenite: Mica sheets are elastic and spring back.
Light-colored mica that peels into paper-thin, transparent and flexible sheets. Its flakes are what make many rocks glitter.
Photo: Robert M. Lavinsky, CC BY-SA 3.0
The clear, bladed variety of gypsum. Thin sheets peel off and bend, and a fingernail scratches it.
Photo: Parent Géry, CC BY-SA 3.0
Key differences
- Mica sheets are elastic and spring back.
Side by side
| Property | Muscovite | Selenite |
|---|---|---|
| Type | Mineral | Mineral |
| Mohs hardness | 2–2.5 | 2 |
| Luster | Vitreous to pearly | Vitreous to pearly |
| Streak | White | White |
| Colors | Clear, Silver, Brown | Clear, White, Gray, Brown |
| Crystal system | Monoclinic | Monoclinic |
| Specific gravity | 2.76–2.88 | 2.3 |
| Formula | KAl₂(AlSi₃O₁₀)(OH)₂ | CaSO₄·2H₂O |
| Found in | Pegmatites of North Carolina; New Hampshire | Great Salt Plains, Oklahoma; Naica, Mexico |
Properties that are the same for both are grayed out.
How to identify muscovite
- Peels into thin sheets that spring back when bent.
- Transparent to silvery and sparkly.
- Soft — scratched by a fingernail across the sheets.
- Stacked 'books' of sheets in pegmatites.
Crystal system: Monoclinic
Full Muscovite guide →How to identify selenite
- Colorless blades or windows you can see through.
- A fingernail scratches it (hardness 2).
- Thin sheets bend and stay bent; they do not spring back like mica.
- Does not fizz in acid and does not taste salty.
Crystal system: Monoclinic
Full Selenite guide →More comparisons
Frequently asked questions
What is the difference between muscovite and selenite?
Muscovite is a mineral with a Mohs hardness of 2–2.5 and a vitreous to pearly luster, usually colorless, silvery or brown. Selenite is a mineral (CaSO₄·2H₂O) with a Mohs hardness of 2 and a vitreous to pearly luster, usually colorless, white, gray or brown.
How can you tell muscovite from selenite?
Mica sheets are elastic and spring back.
Could you tell them apart from a blurry close-up?
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