Rhodochrosite Properties, Formula & Mineral Information

Rhodochrosite — Photo: James St. John · CC BY 2.0

What is Rhodochrosite?

Rhodochrosite is manganese carbonate — MnCO₃ — and almost everything about it is pink. Massive banded material is cut into 'Inca rose' cabochons, but the collector's prize is the gemmy watermelon-red rhombohedron, best known from Colorado's Sweet Home mine.

It is soft, perfectly cleaved, and chemistry does the coloring — pure MnCO₃ is rose; calcium dilutes it toward white. Argentina's Capillitas mine produces stalactites sliced into concentric pink bands.

In one sentence: Pink, rhombohedral, and fizzes — but heavier and slower than calcite.

Physical Properties

The full data table is in the panel alongside. Here’s what those numbers actually mean.

Cleavage. Perfect rhombohedral, like calcite — but SG ~3.6 vs 2.71 gives it away.

Acid. Effervesces, but weakly in cold dilute acid compared to calcite.

Color. Mn²⁺ is the chromophore; iron and calcium mute it toward brown or white.

What It’s Used For

Manganese oreMinor ore where abundant.

LapidaryBanded material cuts striking cabochons and carvings.

Collector specimensSweet Home rhombs rank among the most valuable display minerals.

How to Identify It

Pink to red color with white streakPerfect rhombohedral cleavageFizzes in acid — but slower than calciteBanded stalactites common

Looks like…	But differs because…	Quick test
Rhodonite	A silicate — harder (5.5–6.5), black Mn-oxide veins, no fizz	Acid & hardness
Cobaltocalcite	Cobalt-pink calcite — fizzes vigorously, SG ~2.7	Acid rate