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Chemical Formula | Cu2CO3(OH)2 | |||||
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Composition | Basic copper carbonate | |||||
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Color | Light to dark green, sometimes banded with darker and lighter shades of green | |||||
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Streak | Light green | |||||
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Hardness | 3½ - 4 | |||||
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Crystal Forms and Aggregates |
(Monoclinic) Most common habit is as large crusts of microscopic crystals. Also occurs as
bundles of thin long splinters. Large individual crystals
are very rare and are usually pseudomorphs after Azurite. When they are not pseudomorphs of
Azurite, they are prismatic, tabular, re-entrant twins,
and (most commonly) thin splinters. Also occurs acicular, radiating, reniform, botryoidal, as banded masses, earthy, stalactitic, and as thin films coating other minerals. |
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Transparency | Opaque, although translucent in thin splinters | |||||
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Specific Gravity | 3.9 - 4.0 | |||||
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Luster | Vitreous, silky, or dull | |||||
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Cleavage | 1,1 - basal. Not usually discernible because crystals are tiny. | |||||
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Fracture | Splintery | |||||
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Tenacity | Brittle | |||||
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In Group | Carbonates | |||||
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All About | Malachite is a secondary copper mineral found in oxidized copper
deposits. The massive, botryoidal, reniform, and stalactitic forms are dense intergrowths of
tiny, fibrous needles. Such specimens are virtually
always internally banded in different shades of green, and can be
seen when a specimen is polished or cut open. These bands
give much interest to this mineral as an ornament, owing
to its popularity. The banded specimens are frequently polished or cut into slabs to show the bands. Occasionally, the bands consist of concentric rings; such specimens are highly sought after. Polished, banded Malachite has been carved into ornaments and worn as jewelry for thousands of years, and in some ancient civilizations it was thought to be a protection from evil if worn as jewelry. Malachite is generally found with blue Azurite, and sometimes the two may occur admixed or banded together, forming what is commonly known in the gem and mineral trade as "Azure-malachite". |
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Uses | When found in massive hunks, the banded
variety of Malachite makes a precious ornamental stone.
Small ornamental objects, such as boxes and animal
figures are carved out of this compact stone, and if
properly polished, they are quite valuable. This type of
Malachite is also used as a minor gemstone; being cut
into cabochons and fashioned into necklace beads.
"Azure-malachite" has the same gem applications
as banded Malachite. Malachite is very popular among mineral collectors, especially interestingly shaped and banded specimens. It is also used as an ore of copper and crushed to make a green pigment. |
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Striking Features | Green color, crystal habits, and association with Azurite | |||||
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Complex Tests | Effervesces in cold, diluted hydrochloric acid | |||||
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Popularity (1-4) | 1 | |||||
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Prevalence (1-3) | 2 | |||||
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Demand (1-3) | 1 | |||||
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Distinguishing Similar Minerals |
Brochantite - Doesn't effervesce in hydrochloric acid, otherwise very difficult to distinguish the two minerals. | |||||
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Commonly Occurs With |
Azurite, Chrysocolla, Limonite, Chalcopyrite, Copper, Calcite, Quartz | |||||
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Noteworthy Localities |
There are many places where fine Malachite
comes from. The original material, from which ornaments
and jewelry were made since the earliest times came from
an enormous deposit in the Ural Mountains of Russia. Huge
hunks and massive globular specimens were found there. More recently,
such specimens were found in Tsumeb, Namibia; Shaba,
Zaire; Burra Burra, South Australia; and in Bisbee,
Cochise Co., Arizona. The mines that produce the most
fabulous specimens are the Ongonja Mine in Tsumeb,
Namibia, and the Copper Queen Mine of Bisbee, Cochise
Co., Arizona. In these mines, large Azurite crystals were found pseudomorphed by Malachite. Countries that produce large amounts of Malachite are Zambia, Namibia, Zaire, South Africa, Australia, Germany, Romania, Chile, Mexico, and the U.S. In the U.S., localities include the Tintic District, Juab Co., Utah; Morenci, Greenlee Co., Globe, Gila Co., and Ajo, Pima Co., Arizona; and in New Mexico in Grant and Socorro counties. |
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Picture Icon Links |
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Picture Links | 1. Malachite
on host rock 2. Mat of radiating Malachite crystals |
