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| Prasiolite
is named from the Greek words prasio meaning leek,
referring to the vegetable's green color, and lithos for
stone.
| Discovered
in Prehistory;
IMA
status: Not Valid (trade name). |
|
Chemistry
|
|
|
Chemical
Formula: |
SiO2
+ Fe2+ |
|
Silicon
Dioxide + Iron |
Molecular
Weight: |
60.08 gm
(Quartz) |
Composition: |
Silicon |
46.74 %
|
Si
|
100.00 %
|
SiO2
|
Iron |
??? % |
Fe |
??? % |
FeO |
Oxygen |
53.26 % |
O |
|
|
|
100.00 % |
|
100.00 % |
= TOTAL OXIDE |
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Classification
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|
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Mineral
Classification: |
Oxides
|
Strunz 8th
Ed. ID:
|
4/D.01-10 |
Nickel-Strunz 10th
Ed. ID:
|
4.DA.05 |
|
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites,
bismuthites, sulfites, selenites, tellurites, iodates) D : Metal: Oxygen =
1:2 and similar A : With small cations: Silica family
|
Related
to: |
Quartz
Group
|
Synonyms: |
Green
Quartz
|
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|
Crystal
Data
|
|
|
Crystallography:
|
Trigonal
- Trapezohedal |
Crystal
Habit:
|
Widely
variable; but typically long prismatic with steep pyramidal terminations, but may be short
prismatic to nearly bipyramidal; fibrous (Agate & Chalcedony)
|
Twinning:
|
Very
common, penetration twins on the Dauphiné law, about
[0001], and the Brazil law, with [1120] as contact plane;
contact twins on the Japan law, with [1122] as contact
plane, may be repeated; and several other laws.
|
|
|
Physical
Properties
|
|
|
Cleavage: |
[0110]
Indistinct
|
Fracture: |
Conchoidal
|
Tenacity:
|
Brittle,
tough when massive
|
Moh's
Hardness: |
7.0
|
Density:
|
2.60
- 2.65 (g/cm3) |
Luminescence:
|
may
be Triboluminescent
|
Radioactivity:
|
Not
Radioactive
|
Other: |
Piezoelectric
and Pyroelectric
|
|
|
Optical
Properties
|
|
|
Color: |
Medium
to Dark Green, Olive Green
|
Transparency: |
Transparent
to nearly Opaque |
Luster: |
Vitreous,
waxy to dull when massive |
Refractive
Index: |
1.540 - 1.553 Uniaxial
( + ) |
Birefringence: |
0.0090 |
Dispersion: |
0.013
(low)
|
Pleochroism: |
None
|
|
|
Occurances
|
|
|
Geological
Setting: |
In
hydrothermal veins, epithermal to alpine; characteristic
of granites and granite pegmatites; in sandstones and
quartzites, less abundant in other rock types; in hydrothermal
metal deposits. Common in carbonate rocks; a residual
mineral in soils and sediments. |
Common
Associations: |
Calcite,
Chlorite, Epidote, Feldspars, Fluorite, Micas, Zeolites,
many other species. |
Type
Locality: |
n/a |
Year
Discovered: |
Prehistoric |
View
mineral photos: |
Quartz
Mineral Photos and Locations |
|
|
More
Information
|
|
|
|
Mindat.org
(Quartz) Webmineral.com
(Quartz) |
|
|
Prasiolite
is the green variety of the macro-crystalline Quartz
Group of minerals that also includes Amethyst,
Ametrine,
Citrine,
Rose Quartz and Smoky Quartz. Prasiolite is a green,
macro-crystalline variety of Quartz with fairly large,
well formed crystals, whereas Chrysoprase is
a green cryptocrystalline variety of Quartz, where the
individual crystals are too small to be seen. The term
prase is often wrongly used for any green Quartz
and is from the
Greek word prasinon (or
prason) meaning leek,
referring to the vegetable's green color.
Most
Prasiolite gems on the market are irradiated or heat
treated Amethyst. These heated gems are often refered
to as "green amethyst" or "vermarine"
but are not true Prasiolite. Naturally occuring Prasiolite
is actually quite rare. Natural Prasiolite gets its
green color from iron (Fe2+)
compounds in the chemical mixture. Some colorless quartz crystals contain green
Chlorite inclusions or phantoms. These would not be
considered Prasiolite however.
Natural
Prasiolite crystals are known to be found in Southern Bahia and
Minas Gerais, Brazil; and Lower Silesia in Poland.
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Prasiolite
gems for sale:
We
have not photographed our Prasiolite gems
yet. Please
check back soon.
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