( Fr- malachite; Ger- Malachit/Kupferspat;
Nor- malakitt; Rus- )
( Fr- azurite; Ger- Azurit; Nor- azuritt; Rus- )
MALACHITE, Cu2(CO3)(OH)2; AZURITE, Cu3(CO3)2(OH)2
A. Malachite (width - ca. 7 cm) from Jerome, Arizona. Arizona-Sonora Desert Museum. (© photo by Jeffrey A. Scovil)
B. Azurite and malachite breccia (width - 8 cm). Phelps Dodge Morenci Collection. (© photo by Jeffrey A. Scovil)
C. Malachite lion (ca. 5 x 9 x 2.5 cm) from Congo (formerly, in chronological order, Congo Free State, Belgian Congo, Congo, and Zaire). Carver unknown. Unconventional Lapidarist. (© photo by Cindy Fowler, www.unconventionallapidarist.com)
D. Azurite and malachite free form “Wave carving” (height - ca. 57 cm) by Terry Michael Flaherty. (© photo courtesy www.wehug.com)
DESCRIPTIONS: Although many malachite-rich gemrocks consist almost
wholly of massive malachite, others contain noteworthy percentages of
other minerals, especially azurite. Properties
of compact, massive varieties of these two minerals follow:
Color - diverse green hues, some of which are extremely dark, typically banded
H. 3½ - 4½
Light transmission - opaque
Luster - dull, earthy, pearly to velvetlike, silky, waxy to subvitreous
Miscellany - effervesces with warm HCl; commonly occurs as radial aggregates of spherulitic or botryoidal masses that exhibit radial fibers and concentric bands with alternating dark and light green hues. As already noted, some gemrock malachite is spatially associated with azurite. Also, as noted by Kammerling and Fryer (1995, p.120), minerals such as atacamite, brochantite and pseudomalachite may be (and very likely have been) mistaken for malachite. -- Anyone wishing to check these possibilities should submit their specimen(s) to a professional mineralogist for identification.
Color - diverse blue hues, ranging from azure-blue to very dark blue
H. 3½ - 4
S.G. 3.75 - 4.0 (pure - 3.773)
Light transmission - opaque
Luster - dull, pearly to velvetlike, or waxy to subvitreous
Miscellany - effervesces with cold dilute HCl; most azurite occurs as relatively light blue massive and earthy masses; commonly associated spatially with malachite.
OTHER NAMES: As the title of this entry implies, some of the gemrocks listed below consist predominanly of malachite whereas others contain noteworthy percentages of azurite. Some of these rocks contain other noteworthy constituents. The following are examples of names used for these gemrocks.
USES: Malachite is currently used widely for beads; large cabochons used in pendants, brooches, bolo ties and belt buckles; and as veneer for table tops, etc. Although it is also used for vases, carved figurines etc., many of these items are also made of dual constituent malachite-azurite gemrocks. In addition, malachite has been used with other gemrocks, such as lapis lazuli, rhodochrosite and sugilite, in the production of some high quality intarsias (gemstone inlays).
OCCURRENCES: In weathered or alteration zones of copper-bearing ore deposits. And, as already noted, malachite and azurite are commonly closely associated.
NOTEWORTHY LOCALITIES: At many copper deposits -- e.g., Nizhni-Tagilsk, Siberia (Russia); Tsumeb, Namibia (formerly South West Africa); Katanga district, Congo (formerly Belgium Congo, ... ; Broken Hill, New South Wales, Australia; Cananea district, Sonora state, Mexico; DisJones mine, Berks County, Pennsylvania; Copper Knob mine, Ashe County, North Carolina; Bisbee, Conchise County and Morenci, Graham County, Arizona.
REMARKS: The designation malachite comes
from the Greek μαλάχη (mallow)
because of its green color. Azurite is based on the Persian word
for blue (lazhward) in
allusion to its color.
Some malachite (etc.), as marketed, has been treated with oil, epoxy or has been waxed to enhance its color. Resin-bonded and plastic-impregnated malachite (etc.) that consists of relatively sizable fragments surrounded by smaller pieces and powder has also been fashioned for the marketplace. Some masses consisting largely of malachite have different overall effective hardnesses from layer to layer, and some of these differences are great enough to preclude its use as a gemrock until it has be impregnated or bonded.
Malachite and azurite, both carbonates, are highly susceptible to attack by acids, even dilute acids. This fact, along with the fact that both minerals and mixtures of the two scratch rather easily (H. 3½ - 4) means that great care is necessary when objects are fashioned from them AND items made from them should be those that have limited use -- e.g., for jewelry necklaces, brooches and earrings are fine but rings worn constantly would not retain their original, desired appearances.
Malachite was apparently recovered from mines in the Suez-Sinai area as early as 4000 B.C., and legends cite its use as a cure for convulsions and as a powerful local anaesthetic.
Many natural specimens of these gemrocks are, in my opinion, more attractive than the gems and ornaments fashioned from them. Nonetheless, I must admit that I have seen some remarkably well conceived and fashioned pieces whereby the color-banding has been used rather creatively -- a few in the same general ways that wood is frequently carved to enhance the appearance of the end products.
Aventurine quartz - [superior hardness].
***Barite and gibbsite powder plus and organic (polymer) cement. - [Appearance suffices.].
***Barium sulfate in a polymer matrix. - [Appearance suffices.].
Copper malachite - a misnomer for chrysocolla. - [Appearance suffices.].
Eilat stone - variegated blue and green mixture of chrysocolla and other copper minerals (Kammerling, Johnson & Moses, 1995), from the Gulf of Aqaba (off the northwest end of the Red Sea), was formerly described (and marketed?!?) as impure turquoise or a mixture of malachite and azurite. - [Does not effervesce with HCl, whereas malachite and azurite do.].
***Faience - appropriately colored faience has
been used for "malachite" beads, etc. - [relatively easily
distinguished on the basis of appearance, especially using a handlens].
Gibbsite rock - colored and compressed. - [lower
specific gravity (S.G. ~1.93)].
Howlite malachite - howlite dyed green. - [lower specific gravity (S.G. 2.53-2.59)].
***Plastic - [lower specific gravity and lack of granularity of typical malachite].
Prasemalachite - chalcedony so-to-speak impregnated with malachite. - [superior hardness].
Siliceous malachite - chalcedony chrysocolla only listed here because of the name -- i.e., I have found no record of its ever being represented as malachite.
***Synthetic malachite - from Russia - [S.G. -- 3.87-3.92 for natural versus 3.61-3.70 for synthetic; otherwise virtually indistinguishable from natural malachite except by destructive tests; see Balitskiy et al., 1988 and Chernenko & Melnikov, 2003].
REFERENCE: Il'in, 1994.
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R. V. Dietrich © 2012
Revised: April 16, 2012
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