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| Chemistry:
MgCO3 | Discovered
in 1808;
IMA
status: Valid (pre-IMA; Grandfathered).
Magnesite
is named after its chemical composition; principally
containing
Magnesium.
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Classification
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Mineral
Classification: |
Carbonates
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Strunz 8th
Ed. ID:
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5/B.02-30 |
Nickel-Strunz 10th
Ed. ID:
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5.AB.05 |
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5 : CARBONATES (NITRATES) A : Carbonates without additional
anions, without H2O B : Alkali-earth (and other M2+)
carbonates
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Related
to: |
Calcite
Group: Vaterite, Calcite, Magnesite, Siderite, Rhodochrosite,
Smithsonite, Spaerocobaltite, Gaspeite, Otavite. Gaspeite-Magnesite
Series and Magnesite-Siderite Series.
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Crystal
Data
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Crystallography:
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Trigonal
- Hexagonal - Scalenohedral |
Crystal
Habit:
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Uncommon
as crystals. Crystals usually rhombohedral to 30 cm; rarely
prismatic, tabular or scalenohedral. Typically massive, coarse- to
fine-granular, very compact and porcelainous; earthy to rather chalky; lamellar;
coarsely fibrous.
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Twinning:
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Unproven
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Physical
Properties
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Cleavage: |
[1011]
Perfect, [1011] Perfect, [1011] Perfect
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Fracture: |
Conchoidal
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Tenacity:
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Brittle
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Moh's
Hardness: |
3.5
- 4.5
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Density:
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2.98 - 3.02 (g/cm3) |
Luminescence:
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May
exhibit pale green to pale blue fluorescence and phosphorescence
under UV; may
be Triboluminescent
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Radioactivity:
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Not
Radioactive
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Other: |
Slightly soluble in water with the solubility increasing with the presence of
NaCl, Na2SO4, or CO2. |
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Optical
Properties
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Color: |
Colorless, white, greyish-white, yellowish, pale
green, brown, faintly pink, lilac-rose |
Transparency: |
Transparent,
Translucent |
Luster: |
Vitreous |
Refractive
Index: |
1.509 - 1.700 Uniaxial
( - ) |
Birefringence: |
0.191 |
Dispersion: |
Very
strong
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Pleochroism: |
Visible
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Occurances
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Geological
Setting: |
A
primary mineral in igneous or sedimentary rocks; formed
by metamorphism or alteration of serpentine and peridotite;
uncommon in marine evaporites and hydrothermal veins;
rare in carbonatites. |
Common
Associations: |
Antigorite,
Calcite, “Chlorite”, Dolomite, Talc |
Co-Type
Localities: |
Magnisía (Magnesia) Prefecture, Thessalia (Thessaly)
Department, Greece. Bettolino, Baldissero
Canavese, Canavese District, Torino Province, Piedmont, Italy. |
Year
Discovered: |
1808 |
View
mineral photos: |
Magnesite
Mineral Photos and Locations |
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More
Information
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Mindat.org Webmineral.com |
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Magnesite
is an extremely rare gem that is a member of the Calcite
mineral group that includes Calcite,
Siderite,
Rhodochrosite,
Smithsonite,
Spherocobaltite
and Gaspeite.
Facetable crystals are very rare and faceting is difficult
due to its perfect rhombohedral cleavage. Magnesite
gems are beautiful with huge birefringence and strong
dispersion. Most gems are colorless but may also be
yellowish, pale green or faintly pink. The current main source
of facet grade crystals is Brumado, Bahia, Brazil.
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Magnesite
gems for sale:
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Gem:
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Magnesite |
Stock
#:
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MAGNES-001 |
Weight:
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28.8485
ct |
Size: |
21.15
x 16.57 x 10.44 mm |
Shape: |
Cushion |
Color: |
Pale green |
Clarity: |
VSI |
Origin: |
Brumado,
Bahia, Brazil |
Treatment: |
None
(natural) |
Price: |
$1,120.00
[
Make an offer ] |
Pictures
are of the actual gem offered for
sale. Gem images are magnified to
show detail. |
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An
extemely rare and beautiful gem with very
high birefringence, strong dispersion and
pale green color.
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