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| Scapolite
is named from the Greek words skapos
for rod and lithos for stone, refering
to the stumpy nature of its prismatic crystals.
| Discovered
in 1866 (Marialite);
IMA
status: Not Valid (Mineral Group name) |
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Chemistry
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Chemical
Formula: |
(Na,Ca)4(Si,Al)12O24(Cl,CO3,SO4)
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Sodium
Calcium Aluminum Silicate Carbonate Chloride |
Molecular
Weight: |
877.08 gm
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Composition: |
Sodium |
5.24 % |
Na |
7.07 % |
Na2O |
|
Calcium |
9.14 % |
Ca |
12.79 % |
CaO |
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Aluminum |
15.38 % |
Al |
29.06 % |
Al2O3 |
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Silicon |
22.42 % |
Si |
47.95 % |
SiO2 |
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Chlorine |
4.04 % |
Cl |
4.04 % |
Cl |
|
– |
– % |
Cl |
-0.91 % |
-O=Cl2 |
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Oxygen |
43.78 % |
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/J.13-10
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Nickel-Strunz 10th
Ed. ID:
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9.FB.15
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9 : SILICATES (Germanates)
F : Tektosilicates without zeolitic H2O
B : Tektosilicates with additional anions
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Related
to: |
Scapolite
Group. Marialite-Meionite Series.
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Members
of Group: |
Scapolite
Group: Marialite, Meionite, Silvialite
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Varieties: |
Marialite,
Meionite, Petschite, Wernerite
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Synonyms: |
Dipyre,
Fuscite, Marialite-Meionite Series, Skapolite
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Crystal
Data
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Crystallography:
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Tetragonal
- Dipyramidal
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Crystal
Habit:
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Crystals
prismatic, typically with flat pyramidal terminations,
striated || [001], to 1.5 m; granular, massive.
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Twinning:
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None
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Physical
Properties
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Cleavage: |
Distinct
on {100}, Distinct on {110}
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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
- 6.0
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Density:
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2.50
- 2.62 (g/cm3)
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Luminescence:
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Fluorescent;
commonly
fluoresces orange to bright yellow or red under LW or
SW UV or both; specimens from Tanzania may fluoresce
faint blue under LW UV. |
Radioactivity:
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Not
Radioactive
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Optical
Properties
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Color: |
Colorless,
White, Grey; Pink, Violet, Blue, Yellow, Brown, Orange-Brown;
Colorless in thin section.
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Transparency: |
Transparent,
Translucent, Opaque |
Luster: |
Vitreous,
Resinous, Pearly |
Refractive
Index: |
1.539
- 1.541
Uniaxial ( - )
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Birefringence: |
0.007
- 0.009
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Dispersion: |
Weak to Strong; r > v |
Pleochroism: |
None
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Occurances
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Geological
Setting: |
Typically
in regionally metamorphosed rocks, especially marbles,
calcareous gneisses, granulites, and greenschists. Also
in skarns, some pegmatites, pneumatolytically or hydrothermally
altered mafic igneous rocks, and ejected volcanic blocks.
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Common
Associations: |
Plagioclase,
Garnet, Pyroxenes, Amphiboles, Apatite, Titanite, Zircon
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Common
Impurities: |
Fe,
Ca, K, S
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Type
Locality: |
Pianura, Phlegrean Fields, Naples Province, Phlegrean Volcanic complex, Campania, Italy
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Year
Discovered: |
Marialite:
1866; Meionite: 1801 |
View
mineral photos: |
Scapolite
Mineral Photos and Locations |
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More
Information
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Mindat.org (Scapolite)
Webmineral.com (Scapolite)
Mindat.org (Marialite)
Mindat.org
(Meionite) Mindat.org
(Petschite) Mindat.org (Wernerite)
Webmineral.com (Marialite)
Webmineral.com
(Meionite) |
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The name Scapolite
is often used to describe a single gem type,
but is actually the name of a group or series of minerals.
This group or solid solution series includes Marialite and Meionite and varies between
the sodium chloride rich Marialite and the calcium carbonate
rich Meionite.
Distinguishing the Scapolite minerals from each other is difficult as
they differ only slightly in density and index of refraction.
Scapolite forms in metamorphic rocks from the alteration
of Plagioclase Feldspars.
Scapolite
was once also known by the name Wernerite, but
this name has mostly disappeared from use. Other Scapolite
synonyms such as Mizzonite and Dipyre have also mostly
been dropped from use. Scapolite is the name most often used
by mineralogists and gem collectors.
As a gemstone Scapolite is not well known, but can be very attractive.
It
is available in many colors: yellow, orangy-yellow,
greenish-yellow, bluish-gray, pink, brown, colorless,
and rarely, violet. Its variety of colors may be Scapolite's
best feature since it lacks fire and hardness.
Catseye Scapolite from Burma is
a very rare occurance and has an unusually sharp
eye. A violet to purple variety of Scapolite from Tanzania
is named Petschite.
Petschite is a trade name, not a recognized mineral
species.
Tenebrescent
Scapolite from Afghanistan is also
rarely availabe as colorless crystals that turn
blue after exposure to short wave UV light. The longer it
is exposed, the deeper the color will become. When the
UV light is removed, it slowly turns back to colorless.
This transformation back to colorless may take less
than a minute when exposed to strong sunlight or up
to 30 minutes in dim light. This process is repeatable
as often as desired.
The
name Scapolite is from the Greek words skapos
for rod and lithos for stone, refering
to the stumpy nature of its prismatic crystals. The
name Marialite was given by G. vom Rath, a German
mineralogist, in honor of his wife Maria Rosa.
Meionite is from the Greek word meion
meaning less, because its pyramidal shape is
smaller than that of Vesuvianite
which it resembles. Mizzonite is from the Greek word meizon meaning
greater because the axial ratio is larger than
that of Meionite. The name Wernerite is after Abraham
Gottlob Werner (1750-1817), a German mineralogist.
Scapolite
crystals are available from a number of localities.
Very gemmy violet crystals are available from Badakhshan and
Ningarhar Provinces, Afghanistan. Tenebrescent colorless/blue
crystals are also rarely available from Afghanistan.
Straw yellow to deep yellow crystals can be found
at the Merelani Hills, Lelatema Mts, Arusha Region, Tanzania.
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Scapolite
gems for sale:
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