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| Willemite
was re-named in 1830 by French
born mineralogist Serve-Dieu Abailard
"Armand" Lévy (1795-1841) in honor of William I (Willem) (1772-1843), first
King of the
Netherlands, from 1813 to 1840, where the type locality was located at the time.
| Discovered
in 1824; IMA
status: Valid (pre-IMA; Grandfathered) |
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Composition: |
Zinc |
58.68 % |
Zn |
73.04 % |
ZnO |
|
Silicon |
12.60 % |
Si |
26.96 % |
SiO2 |
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Oxygen |
28.72 % |
O |
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100.00 % |
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100.00 % |
= TOTAL OXIDE |
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Classification
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Mineral
Classification: |
Silicates
(Germanates)
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Strunz 8th
Ed. ID:
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8/A.01-20
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Nickel-Strunz 10th
Ed. ID:
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9.AA.05
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9 : SILICATES (Germanates)
A : Nesosilicates A : Nesosilicates without additional anions; cations in tetrahedral [4] coordination
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Related
to: |
Phenakite
Group.
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Members
of Group: |
Phenakite
Group: Eucryptite, Phenakite, Willemite
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Varieties: |
None
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Synonyms: |
None
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Crystal
Data
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Crystallography:
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Trigonal
- Rhombohedral
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Crystal
Habit:
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Crystals
prismatic, both stout and slender, terminated by rhombohedra
and {0001}, to 10 cm. Coarse to fine granular, disseminated;
in fibrous aggregates, botryoidal, and massive.
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Twinning:
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None
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Physical
Properties
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Cleavage: |
Indistinct
on {0001} and {1120}
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Fracture: |
Irregular/Uneven
to Conchoidal
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Tenacity:
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Brittle
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Moh's
Hardness: |
5.5
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Density:
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3.89 - 4.19 (g/cm3)
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Luminescence:
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Strong
Fluorescence; bright green under both SW UV and LW UV;
may be phosphorescent |
Radioactivity:
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Not
Radioactive
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Optical
Properties
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Color: |
Colorless,
white, yellow, green, reddish brown, black |
Transparency: |
Transparent to Translucent
to Opaque |
Luster: |
Vitreous
to resinous |
Refractive
Index: |
1.691
- 1.730 Uniaxial ( + ) |
Birefringence: |
0.010 - 0.028
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Dispersion: |
Strong
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Pleochroism: |
Colorless
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Occurances
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Geological
Setting: |
Of
secondary origin, especially in zinc deposits developed
in limestones; while uncommon, locally an important
ore of zinc. |
Common
Associations: |
Nasonite,
Glaucochroite, Leucophoenicite (Franklin, New Jersey,
USA); Malachite, Mimetite, Rosasite, Duftite, Cerussite
(Tsumeb, Namibia)
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Common
Impurities: |
Al,
Fe, Mn, Pb, Mg, Ca |
Type
Locality: |
Vieille Montagne (Altenberg; Kelmisberg), Moresnet,
Kelmis, Plombières-Vieille Montagne District, Verviers, Liège Province,
Belgium |
Year
Discovered: |
1824;
re-named Willemite in 1830
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View
mineral photos: |
Willemite
Mineral Photos and Locations |
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Unusual
Gem Categories
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Fluorescent Gems |
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More
Information
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Mindat.org
Webmineral.com
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Willemite
is a rare zinc silicate mineral that is a member of
the Phenakite Group of minerals that also includes Eucryptite
and Phenakite.
It is known and desired by collectors for
its wonderful fluorescence. Willemite fluoresces
a bright green under both short wave (SW) and long wave
(LW) ultra-violet (UV) light. It is
one of the best examples of a fluorescent mineral and
is a must have for collectors of fluorescent minerals
and gems. Willemite is often associated with Calcite
which glows intense red under SW UV light. The
combination of these two minerals glowing bright green
and intense red makes for spectacular specimens. Some Willemite specimens will even show phosphorescence.
Phosphorescence is the ability of a mineral to glow
after the initial light source is removed. The mineral stores the energy of the light and re-emits light for
a short time.
Willemite is found as colorless, white,
gray, various shades of green, yellow, orange and red-brown
crystals. Crystals
can be prismatic, both stout and slender, terminated by rhombohedra,
to 10 cm in length. It is one of the few silicate minerals
that have a trigonal crystal symmetry. This symmetry
is much more common among carbonates than silicates.
Willemite shares the same symmetry with the silicate Dioptase and the closely related silicate Phenakite.
Willemite
was originally named "silicious oxyde of zinc" in 1824 by American
geologists Lardner Vanuxem
(1792-1848) and William Hypolitus Keating (1799-1824). It was re-named in 1830 by French
born mineralogist Serve-Dieu Abailard
"Armand" Lévy (1795-1841) in honor of William I (Willem) (1772-1843), first
King of the
Netherlands, from 1813 to 1840, where the type locality was located at the time. William I (Willem Frederik) was
Prince of Orange-Nassau, the first King of the Netherlands and Grand Duke of Luxembourg.
Willemite
distribution:
in Belgium, from Altenberg, near Moresnet. At Tsumeb
and Guchab, Namibia. From Kabwe (Broken Hill), Zambia.
In the USA, large crystals at Franklin and Sterling
Hill, Ogdensburg, Sussex County, New Jersey; from Balmat,
St. Lawrence County, New York; in Arizona, from the
Mammoth-St. Anthony mine, Tiger, Pinal County, at the
Red Cloud mine, La Paz County, and other minor localities;
in California, at the Ygnacis and Cerro Gordo mines,
Inyo County; in the Tres Hermanas district, Luna County,
New Mexico. From Mont Saint-Hilaire, Quebec, Canada.
In a large deposit at the Puttapa zinc mine, near Beltana,
South Australia. There are many other minor localities.
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Willemite
gems for sale:
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Gem:
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Willemite |
Stock
#:
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WILL-002 |
Weight:
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1.069
ct |
Size: |
7.17 x
5.04
x 3.07 mm |
Shape: |
Oval |
Color: |
Green
w/ Zincite inclusions |
Clarity: |
Moderately
included |
Origin: |
Franklin,
New Jersey |
Treatment: |
None
(natural) |
Price: |
SOLD
(but we have others) |
Pictures
are of the actual gem offered for
sale. Gem images are magnified to
show detail. |
|
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An
extemely rare gem from the foremost occurance
of Willemite: Franklin, New Jersey. This
is a very large gem for Willemite. It is
moderately included with Zincite and does
have a small fracture line across the table
but the very bright yellowish green color
and Zincite inclusions make this a very
rare and interesting gem.
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Gem:
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Willemite |
Stock
#:
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WILL-003 |
Weight:
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0.2140
ct |
Size: |
3.66 x 2.15 mm |
Shape: |
Round |
Color: |
Bright
Yellowish Green |
Clarity: |
I2 |
Origin: |
Franklin,
New Jersey |
Treatment: |
None
(natural) |
Price: |
SOLD
(but we have others) |
Pictures
are of the actual gem offered for
sale. Gem images are magnified to
show detail. |
|
|
An
extemely rare gem from the foremost occurance
of Willemite: Franklin, New Jersey. It is
a very bright yellowish green and moderately included which
is typical for this gem type. Willemite
glows a very bright green in UV light
(second picture).
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Gem:
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Willemite |
Stock
#:
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WILL-001 |
Weight:
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0.322
ct |
Size: |
4.52
x 3.26
x 2.43 mm |
Shape: |
Oval |
Color: |
Pale
Yellow |
Clarity: |
Eye
Clean |
Origin: |
Tsumeb,
Namibia |
Treatment: |
None
(natural) |
Price: |
SOLD
(but we have others) |
Pictures
are of the actual gem offered for
sale. Gem images are magnified to
show detail. |
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A
very rare Tsumeb gem that is eye clean and
well faceted.
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