Comparison · Minerals
Aragonite vs Calcite
Aragonite and Calcite are easy to confuse because both are minerals. Both sit near Mohs 3.5–4, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Below is a side-by-side comparison of their properties and the quick tests that separate them.
Key differences between Aragonite and Calcite
- Both sit near Mohs 3.5–4, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
- Hold a thin edge to the light: Aragonite is Transparent to translucent, Calcite is transparent.
- They overlap in clear, yellow, blue, and pink, but Aragonite also comes in gray and Calcite also comes in orange and green.
- Well-formed crystals give it away: Aragonite is Orthorhombic, Calcite is trigonal.
Aragonite vs Calcite properties
| Property | Aragonite | Calcite |
|---|---|---|
| Type | Minerals | Minerals |
| Mohs hardness | 3.5–4 | 3 |
| Luster | Vitreous to resinous | vitreous |
| Streak | White | White |
| Transparency | Transparent to translucent | transparent |
| Specific gravity | 2.93–2.95 | 2.7 |
| Crystal system | Orthorhombic | trigonal |
| Common colors | Colorless, White, Yellow, Gray, Blue, Pink | Colorless, White, Yellow, Orange, Blue, Green, Pink |
| Rarity | common | common |
| Typical specimen value | $2–$150+ | $2–$100+ |
Which is more valuable?
Aragonite is usually the more valuable of the two: a typical collector specimen runs about $20 against $15 for Calcite, and premium Aragonite can reach $150 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 Calcite
Calcite is one of the most common minerals on Earth, found in sedimentary, metamorphic, and igneous rocks. It's the primary component of limestone and marble.
Aragonite vs Calcite FAQ
Is Aragonite the same as Calcite?
No. Both are minerals, but they are distinct species with different hardness, streak or luster. Both sit near Mohs 3.5–4, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
How can you tell Aragonite from Calcite?
Both sit near Mohs 3.5–4, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Hold a thin edge to the light: Aragonite is Transparent to translucent, Calcite is transparent. They overlap in clear, yellow, blue, and pink, but Aragonite also comes in gray and Calcite also comes in orange and green.
Which is harder, Aragonite or Calcite?
Aragonite is harder: Mohs 3.5–4 against Mohs 3 for Calcite.
Which is more valuable, Aragonite or Calcite?
Aragonite is usually the more valuable of the two: a typical collector specimen runs about $20 against $15 for Calcite, and premium Aragonite can reach $150 or more.
