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| Melanterite
was named in 1850 from the Greek copperas, meaning ferrous sulfate
or black metallic dye.
| Discovered
in 1850;
IMA
status:
Valid (pre-IMA; Grandfathered) |
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Chemistry
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Chemical
Formula: |
Fe2+(SO4)•7(H2O) |
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Hydrated
Iron Sulfate |
Molecular
Weight: |
278.02 gm |
Composition: |
Iron |
20.09 % |
Fe |
25.84 % |
FeO |
|
Hydrogen |
5.08 % |
H |
45.36 % |
H2O |
|
Sulfur |
11.53 % |
S |
28.80 % |
SO3 |
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Oxygen |
63.30 % |
O |
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|
|
100.00 % |
|
100.00 % |
= TOTAL OXIDE |
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Classification
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Mineral
Classification: |
Sulfates
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Strunz 8th
Ed. ID:
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6/C.06-10
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Nickel-Strunz 10th
Ed. ID:
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7.CB.35
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7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates) C : Sulfates (selenates, etc.) without additional anions, with H2O B : With only medium-sized cations
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Related
to: |
Melanterite Group.
Iron analogue of Chalcanthite.
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Varieties: |
Cuprian Melanterite,
Cuprokirovite, Kirovite, Manganoan Melanterite, Mg-bearing Melanterite,
Zincian Melanterite
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Synonyms: |
Copperas,
Green Vitriol, Iron Vitriol, Melantherite, Sulphate of Iron
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Crystal
Data
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Crystallography:
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Monoclinic
- Prismatic
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Crystal
Habit:
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Crystals
are rare, equant, pseudo-octahedral, to short prismatic
[001], showing {120}, {001}, may be thick tabular {010},
{102}, many smaller modifying forms, to 20 cm; commonly
stalactitic, in concretions and crusts, massive, pulverulent,
and as efflorescences.
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Twinning:
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None
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Physical
Properties
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Cleavage: |
On
{001}, perfect; on {120}, distinct
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Fracture: |
Conchoidal
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Tenacity:
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Brittle
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Moh's
Hardness: |
2.0
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Density:
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1.895
- 1.898 (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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Other: |
Soluble
in
water. May dehydrate to the mineral Siderotile.
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Health
Warning: |
CAUTION:
Poisonous!
May contain sulfuric acid. Do not lick or ingest. Do
not touch with bare hands or wash hands immediately
after handling! |
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Optical
Properties
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Color: |
Green,
pale Green, Greenish Blue, Bluish Green, Colorless;
Colorless to pale Green in transmitted light.
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Transparency: |
Transparent
to Translucent, Opaque
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Luster: |
Vitreous
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Refractive
Index: |
1.470
- 1.486 Biaxial ( + )
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Birefringence: |
0.0150
- 0.0160
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Dispersion: |
None
to Weak; inclined, r > v
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Pleochroism: |
None
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Occurances
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Geological
Setting: |
A secondary mineral formed by the oxidation of iron sulfide minerals,
such as pyrite and marcasite, it is found occurring naturally in
sheltered crevices and cavities in sulfidic sedimentary and metamorphic
rocks, and in coal and lignite deposits. It also forms readily on the
walls, timbers, and other structures in mines. |
Common
Associations: |
Pisanite,
Chalcanthite, Epsomite, Pickeringite, Halotrichite,
other sulfates. |
Common
Impurities: |
Cu,
Mg |
Type
Locality: |
n/a
|
Year
Discovered: |
1850
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View
mineral photos: |
Melanterite
Mineral Photos and Locations |
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More
Information
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Mindat.org Webmineral.com
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Melanterite
is one of only a few water soluble sulfate minerals. It
is the iron analog of Chalcanthite. Melanterite is a hydrated iron sulphate mineral
formed after the decomposition
of pyrite or other iron minerals due to the action of surface waters. It
is often found in mines as a post-mining formation on mine walls as encrustations
or stalactites.
It is subject to dehydration and may dehydrate to the mineral Siderotile. Some
specimens my have a beautiful blue-green color and may
be fairly transparent. Faceted gems are very rare and
are extremely difficult to cut due to the softness (Mohs
2.0) and water solubility. Gems should be stored in
an air tight container since they may be subject to
dehydration. Melanterite should be handled with caution
because of the possible presence of sulfuric acid.
Melanterite
occurs at many localities, a few with large crystals.
In Germany, from the Rammelsberg mine, near Goslar,
Harz Mountains. At Falun, Sweden. From Rio Tinto, Huelva
Province, Spain. At Idria, Slovenia. Large crystals
on the island of Cyprus. From Cantiere Conche, Elba,
Italy. At Baia Sprie (Felsóbánya), Romania. From Damar,
Murgul, northeast Anatolia, Turkey. In the USA, at the
Alma mine, Leona Heights, Alameda County, and the Island
Mountain mine, Trinity County, California; from Ducktown,
Polk County, Tennessee; at Butte, Silver Bow County,
Montana; in the Lucky Boy mine, Bingham district, Salt
Lake County, Utah. At volcanoes on the Kamchatka Peninsula,
Russia. From Tierra Amarilla, southeast of Copiapó,
Atacama, Chile.
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Melanterite
gems for sale:
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have not photographed our Melanterite gems. Please
check back soon.
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