Identification guide · Minerals
How to Identify Celestine
Celestine forms tabular to prismatic crystals, often pale blue but also colorless, white, gray, or orange, with a vitreous luster and a white streak. Hardness runs about 3 to 3.5, softer than quartz, and it has distinct cleavage in two directions that yields glassy, stepped surfaces when broken. It reacts only weakly, if at all, with dilute acid, unlike calcite, which fizzes vigorously, offering a useful field test when color alone is ambiguous. Barite is its closest look-alike, distinguished mainly by celestine's lower density.
Celestine identification checklist
| Color | Colorless, Pale blue, White, Gray, Light green, Orange (rare) | Look at a clean, dry surface in daylight. Color zoning, banding or spots are as diagnostic as the hue. |
|---|---|---|
| Luster | Vitreous, pearly on cleavage | Fresh surfaces shine like glass; a dull surface usually means weathering, so chip or wet a corner. |
| Transparency | Transparent to translucent | Hold a thin edge up to a bright light and note whether light passes through. |
| Mohs hardness | 3–3.5 | A copper coin (Mohs 3.5) scratches it, but a fingernail does not. |
| Streak | White | Drag a corner across unglazed porcelain (the back of a bathroom tile) and check the powder color. |
| Cleavage | Perfect on {001}, good on {210} | |
| Fracture | Uneven | |
| Specific gravity | 3.95–3.97 | Heavier than it looks (specific gravity about 3.96). |
| Crystal system | Orthorhombic |
Celestine look-alikes and how to tell them apart
Both sit near Mohs 3–3.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Celestine vs Calcite →
Both sit near Mohs 3–3.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Celestine vs Anhydrite →
Both sit near Mohs 3–3.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Celestine vs Aragonite →
Both sit near Mohs 3–3.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
Celestine identification FAQ
How can you tell if a rock is Celestine?
Check the color (colorless, pale blue, white, and gray), the vitreous, pearly on cleavage luster, a Mohs hardness of 3–3.5 and a white streak. Photographing it with the StoneSnap app gives a match in seconds.
What is the hardness of Celestine?
Celestine has a Mohs hardness of 3–3.5. A copper coin (Mohs 3.5) scratches it, but a fingernail does not.
What is the difference between Celestine and Calcite?
Celestine (Mohs 3–3.5, vitreous, pearly on cleavage luster) and Calcite (Mohs 3, vitreous luster) look alike, but hardness, streak and heft usually separate them. See the full Celestine vs Calcite comparison for a side-by-side table.
Is Celestine worth anything?
Entry-level Celestine specimens sell for around $2, typical collector pieces about $20, and premium examples $150 or more depending on size, quality and locality.
What color is Celestine?
Celestine is most often colorless, pale blue, white, and gray. Color varies with impurities and locality, so confirm with hardness and luster rather than color alone.
