Bornite with Malachite

Mineral Association

Cu5FeS4 with Cu2(CO3)(OH)2

Also known as: Peacock Ore (for Bornite), Copper Carbonate (for Malachite)

Got a photo? Identify rocks instantly with the Rockby app

Description

This refers to the natural occurrence of bornite and malachite together. Bornite, often called 'peacock ore' due to its iridescent tarnish, is a copper iron sulfide. Malachite is a vibrant green copper carbonate hydroxide. When found together, malachite typically forms as an alteration product on or near bornite, indicating the weathering and oxidation of the primary copper sulfide.

How to Identify

Color: Bornite: Freshly broken surfaces are reddish-brown to copper-red, rapidly tarnishing to iridescent purples, blues, and reds (peacock colors). Malachite: Bright green to dark green, often banded.
Luster: Bornite: Metallic. Malachite: Silky, dull, or earthy in massive forms; vitreous to adamantine in crystalline forms.
Texture: Bornite: Typically massive, granular, or disseminated. Malachite: Often botryoidal, stalactitic, fibrous, or massive; sometimes as crusts or coatings.
Crystal Form: Bornite: Isometric system, rarely forms distinct cubic, dodecahedral, or octahedral crystals; usually massive. Malachite: Monoclinic system, rarely forms distinct crystals; typically found in botryoidal, reniform, stalactitic, or massive habits, often with concentric banding.
Cleavage: Bornite: Poor, indistinct, or absent. Malachite: Perfect on {201}, good on {001}.
Geological Environment: Found in the oxidized zones of copper sulfide deposits. Bornite is a primary ore mineral in hydrothermal veins, porphyry copper deposits, and contact metamorphic deposits. Malachite forms secondarily from the weathering of bornite and other copper sulfides in the presence of carbon dioxide and water.

Key Facts

Hardness: Bornite: 3.0-3.25 on Mohs scale. Malachite: 3.5-4.0 on Mohs scale.
Specific Gravity: Bornite: 4.9-5.3. Malachite: 3.9-4.03.
Crystal System: Bornite: Isometric. Malachite: Monoclinic.
Color: Bornite: Reddish-brown to copper-red, tarnishing to iridescent purples, blues, reds. Malachite: Bright green to dark green.
Luster: Bornite: Metallic. Malachite: Silky, dull, earthy, vitreous to adamantine.
Transparency: Bornite: Opaque. Malachite: Translucent to opaque.
Fracture: Bornite: Uneven to conchoidal. Malachite: Uneven to subconchoidal.
Cleavage: Bornite: Poor, indistinct, or absent. Malachite: Perfect on {201}, good on {001}.
Composition: Bornite: Copper iron sulfide (Cu5FeS4). Malachite: Copper carbonate hydroxide (Cu2(CO3)(OH)2).

Quick Check

Color: Bornite: Reddish-brown to copper-red, tarnishing to iridescent purples/blues/reds. Malachite: Bright green to dark green.
Luster: Bornite: Metallic. Malachite: Silky, dull, or earthy.
Streak: Bornite: Grayish-black. Malachite: Light green.

Physical Characteristics

Crystal Habit: Bornite: Massive, granular, disseminated, rarely cubic, dodecahedral, or octahedral crystals. Malachite: Botryoidal, reniform, stalactitic, fibrous, massive, crusts, rarely acicular crystals.
Cleavage Type: Bornite: Indistinct. Malachite: Perfect in one direction, good in another.
Fracture Type: Bornite: Uneven to conchoidal. Malachite: Uneven to subconchoidal.
Tenacity: Bornite: Brittle. Malachite: Brittle.
Luster Type: Bornite: Metallic. Malachite: Silky, dull, earthy, vitreous to adamantine.

Formation

Bornite is a primary copper iron sulfide mineral, typically forming in hydrothermal veins, contact metamorphic deposits, and disseminated in igneous rocks. Malachite is a secondary copper carbonate hydroxide mineral, forming in the oxidized zones of copper ore deposits, often as an alteration product of primary copper sulfides like bornite, chalcopyrite, and chalcocite, in the presence of carbonate-rich waters and atmospheric carbon dioxide.

Usage

Bornite is a significant ore of copper. Malachite is a minor ore of copper, but more importantly, it is used as an ornamental stone, pigment, and for jewelry. The combination of the two is primarily of interest to mineral collectors.

Age Distribution

Formed throughout geological history, often associated with copper mineralization events from Precambrian to Cenozoic eras.

Where to Find

Butte, Montana, USA

Historically a major copper mining district, known for significant bornite and malachite occurrences.

Cornwall, England

Famous for its copper and tin deposits, where bornite and malachite are found.

Tsumeb, Namibia

Renowned for its exceptional mineral specimens, including bornite and malachite.

Katanga Province, Democratic Republic of Congo

A world-class copper belt, producing abundant malachite and associated copper minerals like bornite.

Bisbee, Arizona, USA

Another historic copper mining district with notable occurrences of bornite and malachite.

Finding Tips

Look for Copper Deposits

Focus on areas known for copper mineralization, especially the oxidized zones of these deposits.

Identify Green Stains

Malachite's distinctive green color often forms crusts or stains on other minerals, indicating the presence of copper. Look for these green coatings on reddish-brown or iridescent metallic minerals.

Check for Iridescence

Bornite's characteristic iridescent tarnish ('peacock ore') is a key identifier. Look for metallic minerals with purple, blue, and red hues.

Examine Mine Dumps

Old mine dumps from copper operations are excellent places to find specimens of bornite and malachite.

Similar Rocks

Chalcopyrite with Malachite

Chalcopyrite (CuFeS2) with Malachite (Cu2(CO3)(OH)2)

Also known as: Copper Pyrites with Malachite

Chalcocite with Malachite

Chalcocite (Cu2S) with Malachite (Cu2(CO3)(OH)2)

Also known as: Copper Glance with Malachite

Azurite with Malachite

Azurite (Cu3(CO3)2(OH)2) with Malachite (Cu2(CO3)(OH)2)

Also known as: Blue and Green Copper Carbonate

Scientific Classification

Mineral Class: Bornite: Sulfides. Malachite: Carbonates.
Group: Bornite: Sulfide minerals. Malachite: Carbonate minerals.
Crystal System: Bornite: Isometric. Malachite: Monoclinic.
Chemical Formula: Bornite: Cu5FeS4. Malachite: Cu2(CO3)(OH)2.
Composition: Bornite: Copper (63.3%), Iron (11.1%), Sulfur (25.6%). Malachite: Copper (57.48%), Carbon (5.43%), Hydrogen (0.91%), Oxygen (36.18%).

Explore Bornite with Malachite

Identification Localities & Collecting Look-alikes

Identify rocks anywhere

Free on iOS, Android, and Web. Photo identification, full database, and your personal collection.

Download on theApp Store Get it onGoogle Play Continue onWeb

Open in app