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| Enargite
is named from the Greek word enarges meaning visible,
obvious or distinct, in allusion
to its cleavage.
| Discovery
in 1850;
IMA
status: Valid (pre-IMA; Grandfathered) |
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Chemistry
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Chemical
Formula: |
Cu3AsS4
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Copper
Arsenic Sulfide |
Molecular
Weight: |
393.82 gm
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Composition: |
Copper |
48.41 % |
Cu |
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Arsenic |
19.02 % |
As |
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Sulfur |
32.57 % |
S |
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100.00 % |
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Classification
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Mineral
Classification: |
Sulfides
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Strunz 8th
Ed. ID:
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2/C.14-10
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Nickel-Strunz 10th
Ed. ID:
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2.KA.05
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2 : SULFIDES and SULFOSALTS (sulfides, selenides,
tellurides; arsenides, antimonides, bismuthides; sulfarsenites,
sulfantimonites, sulfbismuthites, etc.) K : Sulfarsenates, Sulfantimonates
A : Sulfarsenates with (As,Sb)S4 tetrahedra
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Related
to: |
Dimorph
of Luzonite.
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Varieties: |
Argentian Enargite,
Stannoenargite
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Synonyms: |
Clarite (of Sandberger),
Garbyite, Guayacanite
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Crystal
Data
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Crystallography:
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Orthorhombic
- Pyramidal
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Crystal
Habit:
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Tabular
on {001}; also prismatic by elongation of [001]; crystals
up to 15 cm. Prism zone typically deeply striated k
[001].
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Twinning:
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Twin
plane {320} common, rarely as interpenetrating pseudohexagonal
trillings.
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Physical
Properties
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Cleavage: |
Perfect
on {110}, Distinct on {100} and {010}, Indistinct on
{001}
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Fracture: |
Irregular/Uneven
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Tenacity:
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Brittle
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Moh's
Hardness: |
3.0
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Density:
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4.45 (g/cm3)
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Luminescence:
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None
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Radioactivity:
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Not
Radioactive
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Health
Warning: |
Contains Arsenic
- always wash hands after handling. Avoid inhaling dust when handling or breaking. Never lick or ingest.
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Optical
Properties
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Color: |
Grayish
Black to iron-Black; in polished section, Gray to pale
Pink-Brown; deep Red internal reflections may be observed.
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Transparency: |
Opaque
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Luster: |
Metallic
to Dull |
Refractive
Index: |
R1–R2:
(400) 24.8–26.2, (420) 26.6–26.0, (440) 26.5–25.6, (460)
26.5–25.9, (480) 26.2–25.8, (500) 25.6–25.6, (520) 24.9–25.3,
(540) 24.4–25.2, (560) 24.0–25.2, (580) 23.8–25.4, (600)
23.8–25.9, (620) 24.1–26.5, (640) 24.6–26.9, (660) 25.2–26.9,
(680) 25.6–26.8, (700) 25.7–26.7
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Birefringence: |
None;
Opaque
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Dispersion: |
None
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Pleochroism: |
Weak
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Anisotrophism: |
Strong;
dark violet red or olice green tones. Color in reflected light:
grey to light pink brown. Internal reflections: deep
red.
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Occurances
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Geological
Setting: |
In
hydrothermal vein deposits formed at medium temperatures.
Also as a late-stage mineral in low-temperature deposits.
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Common
Associations: |
Pyrite,
Sphalerite, Galena, Bornite, Tetrahedrite–Tennantite,
Chalcocite, Covellite, Barite, Quartz
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Common
Impurities: |
Sb,
Fe, Pb, Zn, Ag, Ge
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Type
Locality: |
San Francisco vein, Morococha District, Yauli Province, Junín Department, Peru
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Year
Discovered: |
1850
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View
mineral photos: |
Enargite
Mineral Photos and Locations |
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More
Information
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Mindat.org
Webmineral.com
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Enargite
is a somewhat rare copper
arsenic sulfide mineral
that is dimorphous with Luzonite.
This means the two
minerals that have the same chemical formula (Cu3AsS4)
but different crystal structures. Luzonite is Tetragonal
and Enargite is Orthorhombic. Enargite does not often form well shaped crystals.
However, there are several
localities that produce some fine Enargite clusters.
It is typically found as dark grey to black massive material. The rare crystals are
usually thick tabular, but may also be prismatic. Twinning is common for Enargite and can form a nice star shaped cyclic twin called a trilling.
Enargite has a metallic to dull luster and fairly soft with a Moh's hardness
of only 3.0.
Distribution:
A widespread mineral, may be an important ore of copper,
but not commonly well-crystallized. Only a few localities
can be mentioned. In Peru, from Morococha [TL] and Cerro
de Pasco, with exceptional crystals from the Mina Luz
Angelica, Quiruvilca. In Argentina, in the Sierra de
Famatina, La Rioja Province. In the Philippine Islands,
at Mancayan, Luzon. From the Chinkuashi mine, Keelung,
Taiwan. At Kaize-mura, Nagano Prefecture, and in the
Teine mine, Hokkaido, Japan. In the USA, in splendent
crystals from Butte, Silver Bow County, Montana; in
Utah, in the Tintic District, Juab County; in Colorado,
in fine specimens from a number of mines in the Red
Mountain district, San Juan County In Austria, at Matzenköpfl,
Brixlegg, Tirol. From Bor, Serbia. In Italy, on Sardinia,
at Alghero and Calabona. At Tsumeb, Namibia.
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Enargite
gems for sale:
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