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| Zwieselite
is named for
its first-noted occurrence at Hühnerkobel, nearby Zwiesel
and Rabenstein, Germany.
| Discovered
in 1841; IMA
status:
Valid (pre-IMA; Grandfathered) |
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Chemistry
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Chemical
Formula: |
(Fe2+,Mn2+)2(PO4)F
|
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Iron
Manganese Phosphate Fluoride |
Molecular
Weight: |
225.21 gm
|
Composition: |
Manganese |
12.20 % |
Mn |
15.75 % |
MnO |
|
Iron |
37.20 % |
Fe |
47.85 % |
FeO |
|
Phosphorus |
13.75 % |
P |
31.51 % |
P2O5 |
|
Oxygen |
28.42 % |
O |
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Fluorine |
8.44 % |
F |
8.44 % |
F |
|
— |
—
% |
F |
-3.55 % |
-O=F2 |
|
|
100.00 % |
|
100.00 % |
= TOTAL OXIDE |
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Classification
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Mineral
Classification: |
PHOSPHATES
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Strunz 8th
Ed. ID:
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7/B.03-30
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Nickel-Strunz 10th
Ed. ID:
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8.BB.10
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8 : PHOSPHATES, ARSENATES, VANADATES
B : Phosphates, etc., with additional anions, without H2O
B : With only medium-sized cations, (OH, etc.):RO4 about 1:1
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Related
to: |
Triplite
Group. Triplite-Zwieselite Series.
The Fe2+ analogue of Triplite.
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Members
of Group: |
Triplite
Group: Triplite, Zwiesellite. The Triplite Group may be considered synonymous with Wagnerite Group.
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Varieties: |
None
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Synonyms: |
Zwiselite,
ICSD 4428, PDF 21-811
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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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Cleavable,
massive, to several cm
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Twinning:
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None
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Physical
Properties
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Cleavage: |
Good
on {001}; fair on {010}; poor on {100} (by analogy to
triplite)
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Fracture: |
Irregular/Uneven
to Sub-conchoidal
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Tenacity:
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Brittle
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Moh's
Hardness: |
5.0
- 5.5
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Density:
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3.89
- 3.97 (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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Optical
Properties
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Color: |
Dark
brown, clove-brown, yellowish brown; brownish black
to black if altered
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Transparency: |
Translucent to
Opaque |
Luster: |
Vitreous
to Resinous |
Refractive
Index: |
1.686
- 1.703
Biaxial ( + )
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Birefringence: |
0.017
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Dispersion: |
Moderate to strong; r > v |
Pleochroism: |
Distinct;
yellow-brown to reddish brown |
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Occurances
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Geological
Setting: |
A
primary phosphate in complex zoned granite pegmatites.
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Common
Associations: |
Triphylite,
Huéraulite, Rockbridgeite.
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Common
Impurities: |
Mg,
Ca
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Type
Locality: |
Birkhöhe Quarry (Birkenhöhe Quarry), Zwiesel, Lower Bavaria, Bavaria, Germany
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Year
Discovered: |
1841
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View
mineral photos: |
Zwieselite
Mineral Photos and Locations |
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More
Information
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|
Mindat.org
Webmineral.com
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Zwieselite
is a rare phosphate mineral that is a member of the
Triplite
Group of minerals that also includes Triplite.
In the Triplite-Zwieselite Series,
Zwieselite is the iron rich member and Triplite
is the manganese rich member.
Zwieselite is most often found as translucent to opaque brown massive material
frequently associated with greenish or bluish-gray Triphylite.
Zwieselite is rarely found as gemmy crystals suitable
for faceting.
Localities
for Zwieselite: In Germany, in Bavaria, from Hühnerkobel
and in the Birkhöhe pegmatite, near Zwiesel; at Hörlberg;
from Döfering; and at Hagendorf. From Horní Slavkov
(Schlaggenwald), Czech Republic. In the Mangualde pegmatite,
near Mesquitela, Portugal. At the Tremearne pegmatite,
Breage, Cornwall, England. From the Storm Mountain pegmatite,
Larimer County, Colorado, USA.
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