Comparison · Hydroxide Minerals vs Sedimentary Rocks
Brucite vs Dolomite
Brucite and Dolomite are easy to confuse. Dolomite is harder (Mohs 3.5–4) than Brucite (Mohs 2.5), so Dolomite will scratch Brucite and not the other way round. A copper coin (Mohs 3.5) scratches it, but a fingernail does not. Below is a side-by-side comparison of their properties and the quick tests that separate them.
Key differences between Brucite and Dolomite
- Dolomite is harder (Mohs 3.5–4) than Brucite (Mohs 2.5), so Dolomite will scratch Brucite and not the other way round. A copper coin (Mohs 3.5) scratches it, but a fingernail does not.
- Hold a thin edge to the light: Brucite is translucent, Dolomite is Opaque.
- They overlap in white, yellow, and gray, but Brucite also comes in green and blue and Dolomite also comes in pink and brown.
Brucite vs Dolomite properties
| Property | Brucite | Dolomite |
|---|---|---|
| Type | Hydroxide Minerals | Sedimentary Rocks |
| Mohs hardness | 2.5 | 3.5–4 |
| Luster | vitreous | Vitreous to dull |
| Streak | White | White |
| Transparency | translucent | Opaque |
| Specific gravity | 2.4 | 2.8–2.9 |
| Crystal system | trigonal | — |
| Common colors | White, Pale green, Pale blue, Yellow, Gray | White, Gray, Pink, Brown, Yellow |
| Rarity | uncommon | common |
| Typical specimen value | $5–$250+ | $1–$75+ |
Which is more valuable?
Brucite is usually the more valuable of the two: a typical collector specimen runs about $40 against $10 for Dolomite, and premium Brucite can reach $250 or more.
About Brucite
Brucite is a soft magnesium hydroxide mineral that forms platy, foliated, or fibrous masses with a pearly to vitreous luster. It is usually white but can be pale green, blue, or yellow, and is a notable ore of magnesium.
About Dolomite
Dolomite refers both to the mineral calcium magnesium carbonate, CaMg(CO3)2, and to dolostone, the sedimentary rock composed largely of that mineral. Dolostone typically forms when magnesium-rich water alters existing limestone after deposition, replacing some of the original calcium with magnesium in a process still actively studied by geologists. The rock is usually pale gray, tan, or pinkish and weathers into rounded, pitted outcrops distinct from sharper limestone cliffs.
Brucite vs Dolomite FAQ
Is Brucite the same as Dolomite?
No. Brucite is a hydroxide mineral while Dolomite is a sedimentary rock. Dolomite is harder (Mohs 3.5–4) than Brucite (Mohs 2.5), so Dolomite will scratch Brucite and not the other way round. A copper coin (Mohs 3.5) scratches it, but a fingernail does not.
How can you tell Brucite from Dolomite?
Dolomite is harder (Mohs 3.5–4) than Brucite (Mohs 2.5), so Dolomite will scratch Brucite and not the other way round. A copper coin (Mohs 3.5) scratches it, but a fingernail does not. Hold a thin edge to the light: Brucite is translucent, Dolomite is Opaque. They overlap in white, yellow, and gray, but Brucite also comes in green and blue and Dolomite also comes in pink and brown.
Which is harder, Brucite or Dolomite?
Dolomite is harder: Mohs 3.5–4 against Mohs 2.5 for Brucite.
Which is more valuable, Brucite or Dolomite?
Brucite is usually the more valuable of the two: a typical collector specimen runs about $40 against $10 for Dolomite, and premium Brucite can reach $250 or more.
