Identification guide · Silicate Minerals
How to Identify Scapolite
Scapolite is usually white, pink, and violet with a vitreous luster and is transparent. It has a Mohs hardness of 6. It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will. Its streak is white. It is most often confused with Diopside, Natrolite, and Sillimanite; the tests below separate them.
Scapolite identification checklist
| Color | White, Pink, Violet, Yellow, Gray | 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 | Hold a thin edge up to a bright light and note whether light passes through. |
| Mohs hardness | 6 | It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will. |
| Streak | White | Drag a corner across unglazed porcelain (the back of a bathroom tile) and check the powder color. |
| Cleavage | Distinct on {100} and {110} | |
| Fracture | Conchoidal to uneven | Broken surfaces show smooth, curved, shell-like scoops. |
| Specific gravity | 2.65 | Ordinary rock-like heft (specific gravity about 2.65), similar to quartz. |
| Crystal system | Tetragonal |
Extra tests for Scapolite
Acid test. Fizzes in vinegar or dilute hydrochloric acid because of its carbonate content.
Glass check. Scapolite shares a glassy luster and conchoidal fracture with man-made glass. Glass sits near Mohs 5.5 and often contains round gas bubbles, so a hardness test and a hand lens separate them.
Scapolite look-alikes and how to tell them apart
Both sit near Mohs 6, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Scapolite vs Diopside →
Both sit near Mohs 6, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Scapolite vs Natrolite →
Sillimanite is harder (Mohs 7) than Scapolite (Mohs 6), so Sillimanite will scratch Scapolite and not the other way round. It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will. Scapolite vs Sillimanite →
Both sit near Mohs 6, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
Field tips
- Look for prismatic tetragonal crystals with distinct cleavage and a vitreous luster.
- Fluorescence in yellow, orange, or pink under ultraviolet light can help confirm scapolite.
- Scapolite can resemble feldspar; check crystal form, density, and locality context.
Scapolite identification FAQ
How can you tell if a rock is Scapolite?
Check the color (white, pink, violet, and yellow), the vitreous luster, a Mohs hardness of 6 and a white streak. Photographing it with the StoneSnap app gives a match in seconds.
What is the hardness of Scapolite?
Scapolite has a Mohs hardness of 6. It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will.
What is the difference between Scapolite and Diopside?
Scapolite (Mohs 6, vitreous luster) and Diopside (Mohs 5.5–6.5, vitreous luster) look alike, but hardness, streak and heft usually separate them. See the full Scapolite vs Diopside comparison for a side-by-side table.
Is Scapolite worth anything?
Entry-level Scapolite specimens sell for around $10, typical collector pieces about $70, and premium examples $500 or more depending on size, quality and locality.
What color is Scapolite?
Scapolite is most often white, pink, violet, and yellow. Color varies with impurities and locality, so confirm with hardness and luster rather than color alone.
