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Chemical Formula | Cu3(CO3)2(OH)2 | |||||||||||||||||
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Composition | Basic copper carbonate | |||||||||||||||||
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Color | Blue to very dark blue | |||||||||||||||||
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Streak | Light blue | |||||||||||||||||
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Hardness | 3½ - 4 | |||||||||||||||||
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Crystal Forms and Aggregates |
(Monoclinic) Usually in small crystals, which are in prismatic, tabular, or equidimensional form. Crystals are frequently striated. Other forms are massive, crusty, radiating, fibrous, earthy, columnar, stalactitic, as thin needles, and in ball-like aggregates. Also occurs in dense groups of tabular or prismatic crystals. Azurite commonly forms pseudomorphs over other minerals, retaining the original crystal shape of that mineral it pseudomorphed over. | |||||||||||||||||
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Transparency | Opaque, although translucent in thin splinters | |||||||||||||||||
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Specific Gravity | 3.7 - 3.9 | |||||||||||||||||
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Luster | Submetallic, vitreous, or dull | |||||||||||||||||
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Cleavage | 2,1 ; 3,2 | |||||||||||||||||
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Fracture | Conchoidal or splintery | |||||||||||||||||
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Tenacity | Brittle | |||||||||||||||||
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Other Names |  Chessylite,  Azure
Copper Ore |
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In Group | Carbonates | |||||||||||||||||
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All About | Azurite owes its name to its azure-blue
color. (The European name Chessylite is from a famous
Azurite locality in Chessy, France.) It usually occurs
with green Malachite, which may form green stains or
specks on Azurite crystals or aggregates. The two
minerals sometimes occur admixed or banded together, forming what is called "Azure-malachite"
in the gem and mineral trades. A rarer Azurite mixture,
known as "Bluebird", is
Azurite mixed with dark red Cuprite.
Azurite, "Azure-malachite", and
"Bluebird" all have gem uses. In some localities, the Azurite undergoes a chemical change and loses some hydroxyl, altering the Azurite to Malachite, retaining the crystal shape of the original Azurite. Sometimes, only part of the Azurite is altered to Malachite, while the other part remains as Azurite. Such specimens are green on one end and blue on the other. Linarite specimens are sometimes mistakenly sold as Azurite, since they both occur in the same locations and may strikingly resemble each other. However, simple tests on physical properties can accurately distinguish the two. |
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Uses | Azurite is very popular among collectors,
and is highly in demand. Bright blue pieces are cut into cabochons and beads, and large masses are sometimes
cut into ornamental objects. "Azure-malachite"
is carved as cabochons and beads. Azurite was formerly crushed and used as a blue pigment, but is no longer used for that purpose, since in certain environments is alters to Malachite and turns green. Azurite is an ore of copper. |
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Striking Features | Deep blue color, blue streak, and association with green Malachite | |||||||||||||||||
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Complex Tests | Effervesces in hydrochloric acid and soluble in ammonia | |||||||||||||||||
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Popularity (1-4) | 2 | |||||||||||||||||
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Prevalence (1-3) | 2 | |||||||||||||||||
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Demand (1-3) | 1 | |||||||||||||||||
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Distinguishing Similar Minerals |
Linarite - softer (2½), heavier (5.3 -
5.4), doesn't effervesce in hydrochloric acid Lirconite - lighter and more greenish in color, softer (2½) Connelite - occurs in different crystal forms, doesn't effervesce in hydrochloric acid Cyanotrichite - lighter in color Cornetite - more greenish in color, doesn't effervesce in hydrochloric acid Lazurite and Lazulite - much harder (5 - 6), occur in different mineral environments, and don't effervesce in hydrochloric acid |
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Commonly Occurs With |
Malachite, Cuprite, Calcite, Chalcocite, Chalcopyrite, Chrysocolla, Copper, Limonite | |||||||||||||||||
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Noteworthy Localities |
Fine Azurite specimens have been obtained
from numerous places. These include some of the finest: The largest crystals to date have come from Tsumeb, Namibia, where many forms of this mineral exist. Good specimens have also come from Chessy, France; Laurium, Greece; the Black Forest, Germany; Cornwall, England; Burra Burra, South Australia and Broken Hill, New South Wales, Australia. In Mexico it occurs in the San Carlos Mine in Mazapil, Zacatecas. In the U.S., most fine specimens are from numerous localities in Arizona, but the leading locality by quality and quantity is by far Bisbee, Cochise Co. Other localities in Arizona include Ajo and Tiger, Pinal Co.; and Clifton and Morenci, Greenlee Co. Azurite also occurs in the Rose Mine in Grant Co., New Mexico, and elongated, tabular crystal clusters have come from La Salle Co., Utah. |
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Picture Icon Links |
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Picture Links | 1. Crystal
bunch 2. Bright blue, compact aggregate 3. Crust on rock 4. Large, single crystal 5. "Ball" aggregate 6. "Azure-malachite" |
