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letter above to view the list of gems. |
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| Chemistry:
Ca3Si(CO3)(SO4)(OH)6·12(H2O) | Discovered
in 1878;
IMA
status: Valid (pre-IMA; Grandfathered). Thaumasite is named from
the Greek word thaumazein meaning surprising
in allusion to its rather unusual chemical composition
with carbonate, sulphate and hexahydroxysilicate anions. |
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Classification
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Mineral
Classification: |
Sulfates
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Strunz 8th
Ed. ID:
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8/B.22-90
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Nickel-Strunz 10th
Ed. ID:
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7.DG.15 |
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7 : SULFATES (selenates, tellurates, chromates, molybdates,
wolframates) D : Sulfates (selenates, etc.) with additional anions, with
H2O G : With large and medium-sized cations; with NO3,
CO3, B(OH)4, SiO4 or IO3 15 : Ettringite
Group
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Crystal
Data
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Crystallography:
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Hexagonal
- Dipyramidal
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Crystal
Habit:
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Crystals
prismatic, to 5 cm; typically acicular, radiating; powdery,
compact, massive.
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Twinning:
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None
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Physical
Properties
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Cleavage: |
Poor,
Indistinct
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Fracture: |
Subconchoidal
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Tenacity:
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Brittle
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Moh's
Hardness: |
3.5
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Density:
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1.88
- 1.90 (g/cm3)
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Radioactivity:
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Not
Radioactive
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Optical
Properties
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Color: |
Colorless,
white, pale yellow.
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Transparency: |
Transparent
to Translucent
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Luster: |
Vitreous,
Silky, Greasy
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Refractive
Index: |
1.458
- 1.507 Uniaxial ( - )
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Birefringence: |
0.0390
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Dispersion: |
Very
Weak to None
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Pleochroism: |
None
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Occurances
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Geological
Setting: |
A
very late-stage mineral in some sulfide ore deposits.
In contact metamorphic zones and from the reaction of
geothermal waters or seawaters with basalts and tuffs. |
Type
Locality: |
Bjelke Mine, Åreskutan, Åre, Jämtland, Sweden |
Year
Discovered: |
1878 |
View
mineral photos: |
Thaumasite
Mineral Photos and Locations |
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More
Information
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Mindat.org Webmineral.com
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Thaumasite
is an extremely rare gem and a member of the Ettingite
Group of minerals that includes Charlesite,
Ettringite,
Sturmanite
and Thaumasite.
It was discovered at the Bjelke Mine, Åreskutan, Åre, Jämtland, Sweden
in 1878. It is a soft mineral but seems to harden with
exposure to air. Sources of gem quality crystals include
Paterson, New Jersey and the Kalahari manganese fields
of the Northern Cape Province, South Africa.
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Thaumasite
gems for sale:
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Gem:
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Thaumasite |
Stock
#:
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THAU-001 |
Weight:
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0.220
ct |
Size: |
5.0
x 3.61 x 2.53 mm |
Shape: |
Cut
corner rectangle |
Color: |
Colorless |
Clarity: |
Eye
clean - VS2 |
Origin: |
N'Chwaning
mine, South Africa |
Treatment: |
None
(natural) |
Price: |
$220.00
[
Make an offer ]
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Pictures
are of the actual gem offered for
sale. Gem images are magnified to
show detail. |
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This extemely
rare gem is from the
N'Chwaning Mine in South Africa.
It is mostly eye clean, with just a couple hard to see
inclusions, and very bright.
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