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| Potosíite
is named after Potosí Department, Bolivia where
it was discovered in 1980 at the Andacaba deposit, Linares
Province.
| Discovered
in 1980; IMA
status:
Not Valid (IMA Approved 1981; IMA Discredited 1997) |
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Chemistry
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Chemical
Formula: |
Pb6Sn24+Fe2+Sb25+S16
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Lead
Tin Iron Antimony Sulfide |
Molecular
Weight: |
2,228.89 gm
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Composition: |
Iron |
2.51 % |
Fe |
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Tin |
10.65 % |
Sn |
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Antimony |
10.92 % |
Sb |
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Lead |
55.78 % |
Pb |
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Sulfur |
20.14 % |
S |
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100.00 % |
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Classification
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Mineral
Classification: |
Sulfides
and Sulfosalts
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Strunz 8th
Ed. ID:
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2/C.17-50
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Nickel-Strunz 10th
Ed. ID:
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2.HF.25b
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2 : SULFIDES and SULFOSALTS (sulfides, selenides,
tellurides; arsenides, antimonides, bismuthides; sulfarsenites,
sulfantimonites, sulfbismuthites, etc.) H : Sulfosalts of SnS archetype
F : With SnS and PbS archetype structure units
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Related
to: |
Franckeite Group.
Sn(II)-poor variety of Franckeite.
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Members
of Group: |
Franckeite Group:
Coiraite, Franckeite
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Varieties: |
None
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Synonyms: |
IMA1980-057
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Crystal
Data
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Crystallography:
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Triclinic - Pinacoidal
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Crystal
Habit:
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As
tabular crystals to 3 cm; may be in felted masses.
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Twinning:
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Rare
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Physical
Properties
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Cleavage: |
Perfect
on || (001); less perfect on || (010)
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Fracture: |
n/a
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Tenacity:
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Brittle
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Moh's
Hardness: |
2.5;
Vickers: VHN100=
94 - 115 kg/mm2
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Density:
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6.20 (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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Optical
Properties
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Color: |
Bluish
gray;
grayish black;
white in reflected light
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Transparency: |
Opaque
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Luster: |
Metallic
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Refractive
Index: |
R1–R2:
(400) 38.0–38.9, (420) 37.5–38.5, (440) 37.3–38.2, (460)
37.0–38.0, (480) 36.6–37.7, (500) 36.2–37.4, (520) 35.8–37.1,
(540) 35.2–36.7, (560) 34.7–36.3, (580) 34.3–36.0, (600)
33.9–35.7, (620) 33.5–35.5, (640) 33.1–35.3, (660) 32.7–35.0,
(680) 32.2–34.7, (700) 31.8–34.4
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Birefringence: |
0.000
(Isotropic)
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Dispersion: |
n/a |
Pleochroism: |
Faint; from bluish gray to yellowish gray
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Anisotropism: |
Moderate;
bluish gray to grayish pale yellow
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Occurances
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Geological
Setting: |
On
layered sulfide ore in a complex xenothermal-type hydrothermal
tin deposit associated with subvolcanic granitic intrusive
bodies (Andacaba deposit, Bolivia); in hydrothermal
veins cutting rhyolite intrusions into highly kaolinized
granite (Herb claim, Canada). |
Common
Associations: |
Galena,
Sphalerite, Semseyite, Cerussite, Cassiterite, Quartz
(Andacaba deposit, Bolivia); Galena, Pyrite, Sphalerite,
Arsenopyrite, Quartz (Herb claim, Canada); Arsenopyrite,
Pyrrhotite, Stannite, Jamesonite, Pyrite, Sphalerite,
Kutnahorite, Quartz (Hoei mine, Japan).
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Common
Impurities: |
Ag,
In
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Type
Locality: |
Andacaba deposit, Linares Province, Potosí Department, Bolivia
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Year
Discovered: |
1980
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View
mineral photos: |
Potosíite
Mineral Photos and Locations |
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More
Information
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Mindat.org
Webmineral.com
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Potosíite
is named after Potosí Department, Bolivia where
it was discovered in 1980 at the Andacaba deposit, Linares
Province. Potosíite was approved as a new mineral
species in 1981 by the IMA
but later discredited by the IMA in 1997 and redefined
as a tin (Sn)
poor variety of Franckeite. Similarily, Incaite is a
tin-rich variety of Franckeite. Potosíite and
Franckeite are two of the rarest sulfosalts in the world.
Potosíite had typically been found as massive,
uncrystallized granules of less than 1 mm but a find
at the San José Mine, Oruro City, Cercado Province, Oruro Department, Bolivia
in 2004 produced
exceptionally large, highly lustrous, tabular blades
(some twinned) of Potosíite measuring up
to 13 mm long in association with Franckeite.
Distribution: the type locality [TL] at the
Andacaba deposit, Linares Province, Potosí Department, Bolivia.
At the San José Mine, Oruro City, Cercado Province, Oruro Department, Bolivia.
From the Herb claim, Turnagain River area, Cassiar district,
British Columbia, Canada. At the Oploca mine, Pirquitas
Ag-Sn Deposit, Rinconada Department, Jujuy, Argentina.
From the the Hoei tin mine, Bungo-Ohno City,
Oita Prefecture, Kyushu Region, Japan.
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