Malachite
JewelryWiki Editorial·4 sources·Reviewed 2026-08-04
Extreme birefringence and a copper carbonate composition — soft, and sensitive to acids and heat.
Properties
| Property | Value | Authority |
|---|---|---|
| Mohs hardness | 3½–4 [4] | — |
| Refractive index | 1.655–1.909 [1] | — |
| Specific gravity | 3.25–4.10 [1] | — |
| Chemical formula | Cu2(CO3)(OH)2 [4] | — |
| Crystal system | Monoclinic [2] | — |
| Care cautions | NEVER use an ultrasonic cleaner. GIA names this among the gems commonly impregnated or coated with oil, plastic or wax; those treatments are not permanent and ultrasonic cleaning can strip or damage them. It is also heat-sensitive. Warm soapy water, or a solution formulated for delicate gems. [3] | — |
Sources
- International Gem Society — reference charts (Mohs hardness, specific gravity, refractive index) — International Gem Society (IGS reference charts)
- Wikipedia — mineral article infoboxes (crystal system) — Wikipedia contributors (Wikipedia mineral infoboxes)
- GIA — Ultrasonic Cleaners for Gems: What You Need to Know — Gemological Institute of America (GIA 4Cs, Ultrasonic Cleaners for Gems)
- Handbook of Mineralogy — Mineral Data Publishing / Mineralogical Society of America (Handbook of Mineralogy, Mineral Data Publishing)