Identification guide · Sedimentary Rocks
How to Identify Dolostone
Dolostone is usually tan, gray, and white with a dull luster and is opaque. It has a Mohs hardness of 3.5. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not. Its streak is white. It is most often confused with Dolomite, Limestone, and Oolite; the tests below separate them.
Dolostone identification checklist
| Color | Tan, Gray, White, Cream, Brown | Look at a clean, dry surface in daylight. Color zoning, banding or spots are as diagnostic as the hue. |
|---|---|---|
| Luster | Dull | Compare a fresh surface with glass and metal; this luster is softer than either. |
| Transparency | Opaque | Hold a thin edge up to a bright light and note whether light passes through. |
| Mohs hardness | 3.5 | A steel knife blade (Mohs 5.5) scratches it; a copper coin does not. |
| Streak | White | Drag a corner across unglazed porcelain (the back of a bathroom tile) and check the powder color. |
| Cleavage | Variable by mineral grains | |
| Fracture | Uneven to granular | |
| Specific gravity | 2.85 | Ordinary rock-like heft (specific gravity about 2.85), similar to quartz. |
Extra tests for Dolostone
Acid test. Fizzes only weakly in vinegar or dilute acid unless powdered first.
Dolostone look-alikes and how to tell them apart
Both sit near Mohs 3.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Dolostone vs Dolomite →
Both sit near Mohs 3.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Dolostone vs Limestone →
Both sit near Mohs 3.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Dolostone vs Oolite →
Both sit near Mohs 3.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Dolostone vs Caliche →
Field tips
- Compare with limestone: dolostone often reacts more weakly with dilute acid.
- Look for tan, gray, cream, or buff carbonate rock with granular texture.
- Powdered dolostone may fizz more noticeably than a fresh flat surface.
- Do not confuse the rock dolostone with individual dolomite crystals.
Dolostone identification FAQ
How can you tell if a rock is Dolostone?
Check the color (tan, gray, white, and cream), the dull luster, a Mohs hardness of 3.5 and a white streak. Photographing it with the StoneSnap app gives a match in seconds.
What is the hardness of Dolostone?
Dolostone has a Mohs hardness of 3.5. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not.
What is the difference between Dolostone and Dolomite?
Dolostone (Mohs 3.5, dull luster) and Dolomite (Mohs 3.5–4, vitreous to dull luster) look alike, but hardness, streak and heft usually separate them. See the full Dolostone vs Dolomite comparison for a side-by-side table.
Is Dolostone worth anything?
Entry-level Dolostone specimens sell for around $1, typical collector pieces about $10, and premium examples $75 or more depending on size, quality and locality.
What color is Dolostone?
Dolostone is most often tan, gray, white, and cream. Color varies with impurities and locality, so confirm with hardness and luster rather than color alone.
