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| Arsenopyrite
was named for its composition, a contraction of the antiquated term "arsenical pyrite."
| Discovered
in 1847;
IMA
status: Valid (pre-IMA; Grandfathered) |
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Chemistry
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Chemical
Formula: |
FeAsS
|
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Iron
Arsenide Sulfide |
Molecular
Weight: |
162.83 gm
|
Composition: |
Iron |
34.30 % |
Fe |
|
|
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Arsenic |
46.01
% |
As |
|
|
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Sulfur |
19.69 % |
S |
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|
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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/D.22-10
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Nickel-Strunz 10th
Ed. ID:
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2.EB.20
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2 : SULFIDES and SULFOSALTS (sulfides, selenides,
tellurides; arsenides, antimonides, bismuthides; sulfarsenites,
sulfantimonites, sulfbismuthites, etc.) E : Metal Sulfides, M: S <= 1:2
B : M:S = 1:2, with Fe, Co, Ni, PGE, etc.
|
Related
to: |
Arsenopyrite Group.
Arsenopyrite is closely related to Alloclasite, but is not an exact analogue, because of different As-S and S-As ordering.
|
Members
of Group: |
Arsenopyrite Group:
Arsenopyrite, Gudmundite, Osarsite, Ruarsite
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Varieties: |
Danaite
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Synonyms: |
Arsenical Iron,
Arsenical Pyrites, Arsenomarcasite, Dalarnite, Plinian,
Thalheimite
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Crystal
Data
|
|
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Crystallography:
|
Monoclinic
- Prismatic
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Crystal
Habit:
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Crystals,
to 30 cm, flat tabular to blocky to prismatic, striated
k [001]. Also compact, granular, columnar.
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Twinning:
|
Common
on {100} and {001}; as contact or penetration twins
on {101}; on {012} to produce star-shaped trillings
or cruciform twins.
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Physical
Properties
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Cleavage: |
Distinct
on {101}; {010} in traces.
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Fracture: |
Irregular/Uneven
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Tenacity:
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Brittle
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Moh's
Hardness: |
5.5
– 6.0
|
Vicker's
Hardness: |
VHN100=1081 kg/mm2
|
Density:
|
6.07 (g/cm3)
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Luminescence:
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Not
Fluorescent |
Radioactivity:
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Not
Radioactive
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Health
Warning: |
CAUTION:
Contains Arsenic,
a poisonous element - 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: |
Silver-white
to steel-gray; in polished section, white with faint
yellow tint.
|
Transparency: |
Opaque
|
Luster: |
Metallic
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Refractive
Index: |
R1–R2:
(400) 50.3–51.8, (420) 50.3–51.8, (440) 51.3–51.8, (460)
50.6–51.8, (480) 51.0–51.9, (500) 51.4–51.9, (520) 51.8–51.9,
(540) 52.2–51.9, (560) 52.5–51.9, (580) 53.0–51.8, (600)
53.4–51.6, (620) 53.6–51.5, (640) 53.6–51.3, (660) 53.6–51.3,
(680) 53.4–51.2, (700) 53.2–51.0
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Birefringence: |
0.00
(opaque)
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Dispersion: |
n/a |
Pleochroism: |
Weak;
in white or bluish tint and faint reddish yellow.
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Anisotropism: |
Strong; Color in reflected light: red-violet
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Occurances
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Geological
Setting: |
Of
hydrothermal origin, typically one of the earliest minerals
to form. Found in pegmatites, high-temperature gold-quartz
and tin veins, and in contact metamorphic sulfide deposits;
less commonly of low-temperature hydrothermal origin.
Also in gneisses, schists and other metamorphic rocks.
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Common
Associations: |
Pyrrhotite,
Pyrite, Chalcopyrite, Galena, Gold, Scheelite, Cassiterite,
many other species.
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Common
Impurities: |
Ag,
Au, Co, Sn, Ni, Sb, Bi, Cu, Pb
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Type
Locality: |
n/a
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Year
Discovered: |
1847
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View
mineral photos: |
Arsenopyrite
Mineral Photos and Locations |
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More
Information
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|
Mindat.org
Webmineral.com
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Arsenopyrite
is the most common arsenic bearing mineral found world
wide. However, it is not intentionally mined for that
reason. Arsenopyrite may contain a small amount of gold
as an impurity. Arsenopyrite makes attractive mineral
specimens but is rarely available as a faceted gem.
Arsenopyrite is found in colors of silver-white
to steel-gray and may have a sulfur smell when struck.
Distribution:
The most abundant and widespread arsenic mineral; only
a few localities for large and fine crystals can be
mentioned. In Germany, from Altenberg, Ehrenfriedersdorf,
and Freiberg, Saxony. In the Stari Trg mine, Trepca,
Serbia. From Panasqueira, Portugal. At Sala, Tunaberg,
Stollberg, Boliden, and Nordmark, Sweden. From Stratonik,
Greece. In England, from a number of mines in Cornwall,
and in Devonshire, at Tavistock. In the USA, from Franconia,
Grafton County, New Hampshire and Franklin, Sussex County,
New Jersey. From Hidalgo del Parral and Santa Eulalia,
Chihuahua, Mexico. In Canada, in the Cobalt district,
Ontario. In Japan, large crystals in the Obira mine,
Bungo, Oita Prefecture; the Ashio mine, Tochigi Prefecture;
and many other localities.
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Arsenopyrite
gems for sale:
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have not photographed our Arsenopyrite gems yet. Please
check back soon.
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