Identification guide · Minerals
How to Identify Cavansite
Cavansite is identified almost entirely by its saturated turquoise-to-cobalt blue color, unmatched by common minerals apart from the much softer azurite. It forms spherical or fan-shaped clusters of thin, radiating blades with a vitreous luster and a pale blue streak, and it has a hardness of 3 to 4, distinctly softer than the zeolites it often accompanies. Its close look-alike, pentagonite, shares the same chemistry but crystallizes in a different system with a slightly different blade arrangement, and the two can only be reliably separated with X-ray diffraction.
Cavansite identification checklist
| Color | Bright blue, Deep blue | Look at a clean, dry surface in daylight. Color zoning, banding or spots are as diagnostic as the hue. |
|---|---|---|
| Luster | Vitreous | 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 | 3–4 | A steel knife blade (Mohs 5.5) scratches it; a copper coin does not. |
| Streak | Pale blue | Drag a corner across unglazed porcelain (the back of a bathroom tile) and check the powder color. |
| Cleavage | Perfect, one direction | |
| Fracture | Uneven | |
| Specific gravity | 2.21–2.31 | Noticeably light in the hand for its size (specific gravity about 2.26). |
| Crystal system | Orthorhombic |
Cavansite look-alikes and how to tell them apart
Both sit near Mohs 3–4, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Cavansite vs Calcite →
Both sit near Mohs 3–4, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Cavansite vs Anhydrite →
Apatite is harder (Mohs 5) than Cavansite (Mohs 3–4), so Apatite will scratch Cavansite and not the other way round. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not. Cavansite vs Apatite →
Both sit near Mohs 3–4, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
Cavansite identification FAQ
How can you tell if a rock is Cavansite?
Check the color (bright blue and deep blue), the vitreous luster, a Mohs hardness of 3–4 and a pale blue streak. Photographing it with the StoneSnap app gives a match in seconds.
What is the hardness of Cavansite?
Cavansite has a Mohs hardness of 3–4. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not.
What is the difference between Cavansite and Calcite?
Cavansite (Mohs 3–4, vitreous luster) and Calcite (Mohs 3, vitreous luster) look alike, but hardness, streak and heft usually separate them. See the full Cavansite vs Calcite comparison for a side-by-side table.
Is Cavansite worth anything?
Entry-level Cavansite 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 Cavansite?
Cavansite is most often bright blue and deep blue. Color varies with impurities and locality, so confirm with hardness and luster rather than color alone.
