Comparison · Minerals vs Hydroxide Minerals
Aragonite vs Brucite
Aragonite and Brucite are easy to confuse. Aragonite is harder (Mohs 3.5–4) than Brucite (Mohs 2.5), so Aragonite 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 Aragonite and Brucite
- Aragonite is harder (Mohs 3.5–4) than Brucite (Mohs 2.5), so Aragonite will scratch Brucite and not the other way round. A copper coin (Mohs 3.5) scratches it, but a fingernail does not.
- Aragonite feels noticeably heavier for its size (specific gravity 2.93–2.95 versus 2.4 for Brucite).
- Hold a thin edge to the light: Aragonite is Transparent to translucent, Brucite is translucent.
- They overlap in yellow, gray, and blue, but Aragonite also comes in clear and pink and Brucite also comes in white and green.
- Well-formed crystals give it away: Aragonite is Orthorhombic, Brucite is trigonal.
Aragonite vs Brucite properties
| Property | Aragonite | Brucite |
|---|---|---|
| Type | Minerals | Hydroxide Minerals |
| Mohs hardness | 3.5–4 | 2.5 |
| Luster | Vitreous to resinous | vitreous |
| Streak | White | White |
| Transparency | Transparent to translucent | translucent |
| Specific gravity | 2.93–2.95 | 2.4 |
| Crystal system | Orthorhombic | trigonal |
| Common colors | Colorless, White, Yellow, Gray, Blue, Pink | White, Pale green, Pale blue, Yellow, Gray |
| Rarity | common | uncommon |
| Typical specimen value | $2–$150+ | $5–$250+ |
Which is more valuable?
Brucite is usually the more valuable of the two: a typical collector specimen runs about $40 against $20 for Aragonite, and premium Brucite can reach $250 or more.
About Aragonite
Aragonite is calcium carbonate, CaCO3, crystallizing in the orthorhombic system as a metastable polymorph of the more common mineral calcite. It readily forms in low-temperature settings such as caves, hot springs, and the shells of many marine organisms, and it slowly converts to calcite over geologic time. Twinned crystal clusters resembling six-rayed stars are among its most recognizable forms.
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.
Aragonite vs Brucite FAQ
Is Aragonite the same as Brucite?
No. Aragonite is a mineral while Brucite is a hydroxide mineral. Aragonite is harder (Mohs 3.5–4) than Brucite (Mohs 2.5), so Aragonite 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 Aragonite from Brucite?
Aragonite is harder (Mohs 3.5–4) than Brucite (Mohs 2.5), so Aragonite will scratch Brucite and not the other way round. A copper coin (Mohs 3.5) scratches it, but a fingernail does not. Aragonite feels noticeably heavier for its size (specific gravity 2.93–2.95 versus 2.4 for Brucite). Hold a thin edge to the light: Aragonite is Transparent to translucent, Brucite is translucent.
Which is harder, Aragonite or Brucite?
Aragonite is harder: Mohs 3.5–4 against Mohs 2.5 for Brucite.
Which is more valuable, Aragonite or Brucite?
Brucite is usually the more valuable of the two: a typical collector specimen runs about $40 against $20 for Aragonite, and premium Brucite can reach $250 or more.
