Malachite

Mineral Name: Malachite

Chemical Composition: Cu2CO3(OH)2

Color: Bright green, dark green, blackish green, commonly blended in masses. Green to yellowish green in transmitted light (4).

Streak: Pale green

Hardness: 3.5-4.0

Cleavage/Fracture: Cleavage is in one direction, meaning the minerals crystal lattice allows it to fracture perfectly along one plane-crosswise. Fracture is subconchoidal, meaning it has no natural pattern or plane, it is uneven. For example, obsidian is very well known for its subconchoidal fracture (4).

Crystal Form: Crystals are acicular (which means needle-like shape) to tabular prismatic, (which describes four sides similar in length and width). Malachite crystals can be massive, which means that it has no definable shape and you can not see the crystals without the aid of a magnifying tool. Malachite is often seen in a botryoidal shape, which means they form like a cluster of grapes and look like bubbles. This mineral can also grow as a stalactitic shape that resembles icicles (4).

Crystal class: Prismatic mineral that shows a uniform cross-section (3).

Crystal system: Monoclinic, which is a three dimensional geometric arrangement having three unequal axes, with at right angles to the other two (3).

Luster: Adamantine to vitreous, silky if fibrous, dull to earthy if massive (4).

Special Features: Malachite is an oxidation of copper ore that can have parallel bands and round concentric eye-like rings (3). It effervesces when in contact with cold dilute hydrochloric acid (3).

Varieties: Malachite is known to be found mixed with minerals found in copper ores such as azurite (it becomes known as azurmalachite), turquoise, chrysocolla, and pseudomalachite (3). Other varieties of malachite to be noted are atlaserz (German name for the malachites fibrous variety), lime-malachite (impure malachite), mysorin (impure malachite), and zincian malachite (zinc bearing variety of malachite) (7).

Mineral Group: Malachite is part of the carbonates mineral group, which is classified by having one or more metallic elements plus a carbonate radical (CO3) (3). The carbonates are divided into four groups; Calcite, Aragonite, Nitrate, and Boraite. Carbonates are known to be soft and brittle, also the carbonate causes them to effervesce with acid.

Environment: Malachite is known to form shallowly in the Earth above copper deposits in oxidizing areas and is commonly near limestone, a rock which supplies the carbonate product that reacts with copper ore to make malachite. It will sometimes form within limestone cracks, depending on the chemical composition in the limestone. Malachite is a secondary carbonate of copper ore (5).

Associated Rock types: Malachite is found within or around copper ore as well as limestone. It is associated with quite a few minerals including azurite, bornite, calcite, chalcopyrite, cuprite, copper, and a assortment of oxidized irons (3).

Occurrence in North America: Malachite is found and mined at the Copper Queen Mine in Bisbee, Arizona (7). It also can be found in New Mexico, Michigan, North Carolina and New Hampshire (7).

Economic Uses: Malachite is a softer mineral which enables it to be carved and molded for jewelry (3). Malachite is mainly used in the making of jewelry where it is cut into cabochons, beads, and small ornate carved animals, sculptures and boxes (3). The ancient Egyptians prized malachite jewelry and believed the mineral represented new life, joyfulness, fertility and vegetation (1). Ground malachite was used as a pigment in paintings and makeup (1). Malachite pigment, which was especially popular in paintings and used in Egyptian tombs during the 15th and 16th centuries, was made from ground malachite (3). Nowadays it is sold to painters who specialize in the painting style of the old masters.

Industrial Uses: Malachite is a minor ore of copper (4). The mining of copper ore consists of two ways of extraction: open pit and underground mining. After large rocks of ore are extracted from the mine they are broken down into smaller ore chunks for easier processing. From there the ore is sent off to be smelted for a concentrate of sulfide ore as well as a solvent extraction to get oxide ore leach solution (9). After smelting comes refining. At this point copper gets melted and cast into anodes (sheets or bricks). The final part of refining send the anodes from smelting to be turned into high purity copper cathodes (sheets) through the process of electrolysis (9). From this point the refined copper gets sent off to companies to be turned into parts and products for everyday use (9).

First Notable Identification: Malachite is mentioned in Exodus 39:11-21 where malachite is used along with sapphire and a moonstone in the adornment of the breastpiece of Aaron (8). It’s name comes from the Greek word “Mallow”, meaning green and referring to its similarity to the leafs of the mallow plant (1). Malachite was notably discovered in Russia in the foothills of the Ural mountains in 1635 (6).

How We Identified It: Malachite has a unique and special appearance with the concentric rings that appear in the stone and it’s exquisite green color. It has a marbled appearance in some instances and is spectacularly beautiful when carved and sculpted.

Don’t Confuse It With: Brochantite is also a oxidation of copper and it is very hard to tell it apart from Malachite. Brochantite is green in color and is found within the same rocks as malachite is found. The only way to tell them apart is that Brochantite will not bubble when in contact with hydrochloric acid (4).