Aragonite vs Strontianite
Aragonite and Strontianite are commonly confused, and 1 measured property separates them — density most clearly.
Aragonite vs Strontianite
Aragonite
CaCO3
The other calcium carbonate — same composition as calcite, different structure, and the form most shells are built from.
Strontianite
SrCO3
Strontium carbonate, named after the Scottish village it was found in — and the reason a firework burns red.
| Property | Aragonite | Strontianite |
|---|---|---|
| Crystal system Categorical values can be listed side by side but not ordered or subtracted. | orthorhombic | orthorhombic |
| Density | 2.93–2.95 g/cm³ | 3.74–3.78 g/cm³ higher |
| Lustre Categorical values can be listed side by side but not ordered or subtracted. | vitreous | vitreous |
| Mohs hardness Mohs hardness is an ordinal scale: values can be ranked, but differences and ratios between them are not meaningful. | 3.5–4 | 3.5–4 |
| Streak Categorical values can be listed side by side but not ordered or subtracted. | white | white |
Why these get confused
near-identical structure and habit; the distinction is the flame, crimson against calcium's orange
The confusion is a real and documented one, not a resemblance we have invented.