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Click on a
letter above to view the list of gems. |
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| Chemistry:
CaBe(PO4)F
or CaBe[(F,OH)|PO4] | Discovered
in 1828;
IMA
status: Valid (pre-IMA; Grandfathered). Herderite is named after
Sigmund August Wolfgang von Herder (1776-1838), a mining official
in Freiburg, Saxony, Germany. |
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Classification
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Mineral
Classification: |
Phosphates |
Strunz 8th
Ed. ID:
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7/B.01-10
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Nickel-Strunz 10th
Ed. ID:
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8.BA.10 |
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8 : PHOSPHATES, ARSENATES, VANADATES B : Phosphates, etc.,
with additional anions, without H2O A : With small and
medium-sized cations
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Related
to: |
Herderite-Hydroxylherderite
Series. The Fluorine-dominant analogue of Hydroxylherderite.
Herderite is isotypic with Datolite.
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Crystal
Data
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Crystallography:
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Monoclinic
- Prismatic |
Crystal
Habit:
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Stout prismatic crystals,
thick tabular. Commonly
pseudo-orthorhombic in aspect, rarely monoclinic; pseudo-hexagonal at
times. Also occurs as botryoidal or spheroidal aggregates with a radial-fibrous
structure.
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Twinning:
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On [100] or [001] as fishtail contact. Most crystals are twinned; however, some
exhibit no outward signs of this morphology.
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Physical
Properties
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Cleavage: |
Imperfect,
Fair; [110] Interrupted
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Fracture: |
Sub-Conchoidal
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Tenacity:
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Brittle
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Hardness
(Mohs): |
5.0 - 5.5 |
Density:
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2.95 - 3.02 (g/cm3) |
Luminescence:
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Fluoresces
violet under UV; cathodoluminesces and phosphoresces
pinkish orange under X-rays. |
Radioactivity:
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Not
Radioactive |
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Optical
Properties
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Color: |
Colorless,
pale Yellow, Yellowish Green, light Green
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Transparency: |
Transparent
to Translucent |
Luster: |
Vitreous |
Refractive
Index: |
1.556
- 1.620 Biaxial ( - ) |
Birefringence: |
0.033 |
Dispersion: |
Moderate;
r > v; 0.017 |
Pleochroism: |
None
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Occurances
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Geological
Setting: |
Complex granitic pegmatites. |
Common
Associations: |
n/a |
Type
Locality: |
Sauberg Mine, Ehrenfriedersdorf, Erzgebirge, Saxony,
Germany |
Year
Discovered: |
1828 |
View
mineral photos: |
Herderite
Mineral Photos and Locations |
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More
Information
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Mindat.org Webmineral.com |
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Herderite
is a very rare phosphate collectors gem. It is a very attractive gem
but too soft for jewelry ware. It is found in many colors;
yellow, green, blue, pink, pale violet and colorless.
Currently, most material is from Brazil, although it
is found in several localities around the world including
pale yellow crystals from Maine, USA. The most notable
occurances of gem quality crystals are Minas Gerais, Brazil
and Skardu District, Baltistan, Northern
Areas, Pakistan.
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Herderite
gems for sale:
please click on picture
|
Gem:
|
Herderite |
Stock
#:
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HERD-001 |
Weight:
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4.3260
ct |
Size: |
12.96
x 10.16
x 5.81 mm |
Shape: |
Trillion
(modified) |
Color: |
Yellowish
Green |
Clarity: |
Eye
Clean, almost Loupe Clean |
Origin: |
Minas
Gerais, Brazil |
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. |
|
please click on picture
|
Please
click on the pictures above for larger views.
A
very rare collector's gem from Minas
Gerais, Brazil. This beautiful gem is
very large and clean for the type. It
is very bright and has good color and great
clarity.
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Gem:
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Herderite |
Stock
#:
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HERD-002 |
Weight:
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2.1745
ct |
Size: |
7.81
x 7.74
x 4.25 mm |
Shape: |
Square/Emerald |
Color: |
Yellowish
Green |
Clarity: |
Eye
Clean to VVS |
Origin: |
Minas
Gerais, Brazil |
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. |
|
|
A
very rare collector's gem from Minas
Gerais, Brazil. This beautiful gem is
very bright and has good color and clarity.
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|
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