THE MINERAL ANTLERITE

  • Chemistry: Cu3SO4(OH)4, Copper Sulfate Hydroxide.
  • Class: Sulfates
  • Uses: A minor ore of copper and as mineral specimens.
  • Specimens

Antlerite has been an important ore of copper and forms nice mineral specimens. It typically forms tabular to acicular or fibrous crystals. The acicular crystals often form aggregates of randomly organized coatings and tufts. Its green color is usually a deep and attractive shade. It is formed from the oxidation of copper ore minerals along with other oxidation zone minerals. Once thought to be a rare mineral, antlerite was discovered to be the chief ore at the Chuquicamata copper mines in Chile. Since then its presence has been confirmed at several other copper mines around the world.

Antlerite is similar to other green copper minerals that form in oxidation zones such as the carbonate mineral malachite, the halide mineral atacamite and the closely related sulfate mineral brochantite. This brings up a number of identification problems. Acicular malachite will effervesce in warm hydrochloric acid and antlerite will not. Atacamite is slightly softer and is usually less transparent. Brochantite is all but indistinguishable by ordinary means although its terminations are typically more rounded than the terminations of antlerite.

PHYSICAL CHARACTERISTICS:

  • Color is a bright emerald green or dark green to almost black.
  • Luster is vitreous.
  • Transparency: Crystals are transparent to translucent.
  • Crystal System is orthorhombic; 2/m 2/m 2/m
  • Crystal Habits include small tabular crystals and acicular or fibrous crystal aggregates that form into coatings and tufts. Also found in veins and as reniform, massive or granular specimens.
  • Cleavage is perfect in one direction and poor in another.
  • Fracture is uneven.
  • Hardness is 3.5
  • Specific Gravity is approximately 3.9 (above average for translucent minerals)
  • Streak is pale green.
  • Other Characteristics: Does not effervesce in hydrochloric acid and crystals can be vertically striated.
  • Associated Minerals are limonite, brochantite, cuprite, malachite, gypsum, chalcanthite, atacamite and azurite.
  • Notable Occurrences include Chuquicamata, Chile; Mexico and the Antler mine (from where it gets its name) and Bisbee, Arizona, Nevada, California, New Mexico and Utah, USA.
  • Best Field Indicators are crystal habit, associations, hardness, cleavage, non-reaction to hydrochloric acid and color.
ANTLERITE specimens:
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ANTLERITE specimen anl-1
$ 49.00
Dims: 1.9 x 1.1 x 0.8" (4.9 x 2.9 x 2.0 cm)
Wt: 1.0 oz. (28 g)
Mex-Tex Mine, Bingham, Socorro County, New Mexico, U.S.A.
A crust of tiny, intergrown Antlerite crystals rests on the quartz base of this thumbnail specimen. These crystals do not exceed 0.1" (3 mm) in length and are in good condition, though a few spots of damage are obvious. The crystals are generally acicular and fibrous, and their form is not well defined, if at all. They have a moderately pale green color and a dull, silky luster, and are essentially opaque- actually, the crust strongly resembles malachite. The quartz base on which they rest is actually a partial druse that shows good hexagonal form.
no photo
anl-1 ($ 49.00)
Mex-Tex Mine, Bingham, Socorro County, New Mexico, U.S.A.
ANTLERITE specimen anl-2
$ 70.00
Dims: 2.9 x 1.8 x 1.3" (7.3 x 4.6 x 3.2 cm)
Wt: 2.8 oz. (80 g)
Mex-Tex Mine, Bingham, Socorro County, New Mexico, U.S.A.
A matted fibrous crust of Antlerite covers the quartz base of this small cabinet specimen. A few crystalline needles are visible, but most of the material appears to be matted and formless. Its green color varies in depth from pale to moderate, and it has a dull luster and appears to be opaque. The Antlerite rests on a cluster of stubby quartz crystals that extend from the base.
no photo
anl-2 ($ 70.00)
Mex-Tex Mine, Bingham, Socorro County, New Mexico, U.S.A.
ANTLERITE specimen anl-3
$ 40.00
Dims: 2.1 x 1.3 x 1.1" (5.4 x 3.2 x 2.7 cm)
Wt: 1.5 oz. (44 g)
Mex-Tex Mine, Bingham, Socorro County, New Mexico, U.S.A.
Several tight clusters and countless tiny crystals of Antlerite are scattered on the quartz base of this hand specimen. These crystals do not generally exceed 1 mm in length, though one acicular aggregate suggests lengths of about 2 mm or so. Though extremely small and often intergrown, their orthorhombic form appears to be very good. All have a deep green coloration and a pearly-to-vitreous luster, and are at least translucent as individuals. The quartz base has several stubby crystals extending from it, and contains a small amount of galena.
no photo
anl-3 ($ 40.00)
Mex-Tex Mine, Bingham, Socorro County, New Mexico, U.S.A.
ANTLERITE specimen anl-4
$ 50.00
Dims: 2.4 x 1.7 x 1.6" (6.1 x 4.3 x 4.0 cm)
Wt: 4.6 oz. (128 g)
Mex-Tex Mine, Socorro County, New Mexico, U.S.A.
Countless tiny Antlerite crystals make up crusts that partly coat the lead-bearing base of this hand specimen. These crystals are so small that a loupe is needed to properly study them, and there are actually very few. Most of the material has either a massive or reniform habit, with nodules that do not exceed 1 mm in diameter. The Antlerite has a dark green color that is not quite emerald-green and a generally waxy to matte luster, and it is opaque to all intents and purposes. The Antlerite is accompanied by several other minerals, including calcite, possible malachite, anglesite and galena, which makes up much of the mass of the piece.
no photo
anl-4 ($ 50.00)
Mex-Tex Mine, Socorro County, New Mexico, U.S.A.
ANTLERITE specimen anl-5
$ 57.00
Dims:3.0x1.2x1.2" (7.6x3.0x3.0 cm)
Wt: 4.1oz. (115g)
Mex-Tex mine, Bingham, Socorro cty., New Mexico
This specimen consists of microcrystalline antlerite on a quartz matrix. Also associated with the antlerite are dark blue crystals that I believe are linarite. The antlerite is in the form of tiny radiating nodules around and on the blue crystals. The antlerite crystals are too small for effective study, even with a loupe. There is no damage to the primary group of antlerite crystals.
no photo
anl-5 ($ 57.00)
Mex-Tex mine, Bingham, Socorro cty., New Mexico

 


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