Malachite: properties, varieties and value factors

Key properties

Chemical formula	Cu2CO3(OH)2
Crystal system	Monoclinic
Mohs hardness	3.5-4
Toughness	Poor
Refractive index	1.655-1.909
Birefringence	0.2540
Optic character	Biaxial negative (effectively opaque in gem material) (-)
Specific gravity	3.25-4.10
Cleavage	Perfect {201} and fair {010} — almost never visible in the massive gem material
Fracture	Uneven to subconchoidal; splintery across fibrous bands
Habit	Botryoidal, stalactitic and massive aggregates; individual prismatic crystals rare and collector items
Lustre	Dull to vitreous; silky on fibrous surfaces; polish: Vitreous to silky; fibrous layers can give a soft chatoyant sheen
UV fluorescence	Inert
Pleochroism	None (opaque)
Cause of colour	Idiochromatic — copper (Cu2+) in the crystal structure; the mineral cannot occur without its green
Typical inclusions	Concentric curved banding in alternating light and dark greens • intergrown blue azurite (azurmalachite) • fibrous radial structure
Stability	Stable to light. Attacked by acids: dilute HCl effervesces and dulls the surface. Heat sensitive — darkens and can crack under a torch
Heat sensitivity	High
Care and cleaning	Warm soapy water only; never ultrasonic or steam. Wipe after wear; store away from harder stones
Availability	Plentiful — the Congo supplies generous rough for cabochons, beads and carvings
Recognition	Well known — the banded green ornamental stone most customers recognise on sight

Varieties

Malachite

Colour	vivid light to dark slightly bluish green, almost always banded in two or more tones
Transparency	opaque
Clarity type	Opaque — value rides on banding contrast and polish, not clarity
Phenomena	None (fibrous structure can give a sheen or weak chatoyancy, not a formal phenomenon grade)
Appearance	Grape-jelly botryoidal surfaces in rough; cut stones show silky concentric 'eye' banding from bright apple-green to near-black green
Trade names	Peacock stone (banded blue-green material) • azurmalachite (intergrown with azurite)
Misnomers	Pseudo-emerald (archaic, essentially obsolete)
Typical sizes	Beads and cabs from a fraction of a carat to very large; rough masses allow huge carvings, slabs and table tops
Cutting styles	Cabochons cut across the banding • beads • carvings • inlay • boxes • tablets
Key separations	Curved or angular banding plus effervescence in dilute HCl is usually enough. vs chrysocolla-in-quartz (gem silica): quartz areas RI 1.54-1.55 and hardness 7. vs dyed green howlite or dyed onyx marble: banding looks painted and flat, RI 1.5-1.6, colour in cracks. vs synthetic Russian malachite: unnaturally regular chevron banding — laboratory-grown since Soviet times
Sources (localities)	DR Congo (Kolwezi, Katanga) • Russia (Urals) • Zambia • Namibia • Australia (Burra, Broken Hill) • Mexico • USA (Arizona: Bisbee, Morenci) • France • Israel (Timna)
Availability	Plentiful
Market notes	Sold by piece for carvings more often than by carat; Congo material dominates. Synthetic malachite circulates — quote natural only after checking banding
Care notes	Soft and brittle: protect in settings, keep from acids and heat, expect a re-polish after years of wear
In short	The banded green copper carbonate — instantly recognised, inexpensive and plentiful from the Congo. Its softness and acid sensitivity call for protective settings and gentle care.

Size (ct)	USD per carat	Tier	As of
1.00–10.00	$0.50 – $5.00	commercial cabochons and beads	2026-10-26
10.00–100.00	$5.00 – $20.00	fine banded cabs, boxes, carvings	2026-10-26

Retail market survey, per carat unless noted. Ranges describe what commercial to fine stones trade at; exceptional stones and provenance premiums sit above them.

Sources

GIA gem encyclopedia · mindat.org · Wikipedia

Data compiled and fact-checked against gemmological literature, October 2026 (JDMIS gem reference). Properties are ranges accepted in gemmological practice; individual stones vary.

Key properties

Varieties

Malachite

Sources

See also