Celestine
Sulfate · SrSO₄ · also: Celestite
Celestine is strontium sulfate, loved for its delicate sky-blue crystals that famously line the insides of large geodes.
What is celestine?
Celestine (or celestite) is strontium sulfate, named for its heavenly pale-blue colour. It forms glassy tabular crystals and spectacularly lines geodes, such as the enormous crystal-filled geode on South Bass Island, Ohio. It is the chief source of strontium.
Properties
- Chemical formula
- SrSO₄
- Category
- Sulfate
- Hardness (Mohs)
- 3–3.5
- Crystal system
- Orthorhombic
- Lustre
- Vitreous to pearly
- Streak
- White
- Colour
- Pale sky-blue, white, colourless
- Cleavage / fracture
- Perfect
How to identify celestine
- →Soft sky-blue, glassy tabular or prismatic crystals.
- →Perfect cleavage; white streak; hardness 3–3.5.
- →Heavier than similar-looking minerals (strontium content).
- →Often lines the inside of geodes.
Where celestine is found
Notable localities include Madagascar, Ohio (USA), Sicily and the UK (Bristol area).
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