Identification guide · Silicate Minerals
How to Identify Tremolite
Tremolite is usually white, gray, and green with a vitreous luster and is translucent. It has a Mohs hardness of 5.5. 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 Actinolite, Diopside, and Microcline; the tests below separate them.
Tremolite identification checklist
| Color | White, Gray, Green, Pink | 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 | Translucent | Hold a thin edge up to a bright light and note whether light passes through. |
| Mohs hardness | 5.5 | 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 | Perfect | |
| Fracture | Splintery | |
| Specific gravity | 3 | Ordinary rock-like heft (specific gravity about 3), similar to quartz. |
| Crystal system | Monoclinic |
Tremolite look-alikes and how to tell them apart
Both sit near Mohs 5.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Tremolite vs Actinolite →
Both sit near Mohs 5.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Tremolite vs Diopside →
Both sit near Mohs 5.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Tremolite vs Microcline →
Both sit near Mohs 5.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
Field tips
- Look for bladed, columnar, or fibrous crystals with two amphibole cleavages meeting near 56 and 124 degrees.
- White to gray color and a splintery feel help distinguish tremolite from pyroxenes.
- Association with metamorphosed dolomitic limestone supports identification.
Tremolite identification FAQ
How can you tell if a rock is Tremolite?
Check the color (white, gray, green, and pink), the vitreous luster, a Mohs hardness of 5.5 and a white streak. Photographing it with the StoneSnap app gives a match in seconds.
What is the hardness of Tremolite?
Tremolite has a Mohs hardness of 5.5. 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 Tremolite and Actinolite?
Tremolite (Mohs 5.5, vitreous luster) and Actinolite (Mohs 5–6, vitreous to silky luster) look alike, but hardness, streak and heft usually separate them. See the full Tremolite vs Actinolite comparison for a side-by-side table.
Is Tremolite worth anything?
Entry-level Tremolite specimens sell for around $8, typical collector pieces about $40, and premium examples $250 or more depending on size, quality and locality.
What color is Tremolite?
Tremolite is most often white, gray, green, and pink. Color varies with impurities and locality, so confirm with hardness and luster rather than color alone.
