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Scapolite (Mineral Group)
Current inventory:  0 gems
 

Scapolite

  
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)

 

Chemistry

 

 

Chemical Formula:

(Na,Ca)4(Si,Al)12O24(Cl,CO3,SO4)

 

Sodium Calcium Aluminum Silicate Carbonate Chloride

Molecular Weight:

877.08 gm

Composition:

Sodium

5.24 %

Na

7.07 %

Na2O

 

Calcium

9.14 %

Ca

12.79 %

CaO

 

Aluminum

15.38 %

Al

29.06 %

Al2O3

 

Silicon

22.42 %

Si

47.95 %

SiO2

 

Chlorine

4.04 %

Cl

4.04 %

Cl

 

  %

Cl

-0.91 %

-O=Cl2 

 

Oxygen

43.78 %

O

 

 

 

 

100.00 %

 

100.00 %

= TOTAL OXIDE

 

 

Classification

   

   

Mineral Classification:

Silicates (Germanates)

Strunz 8th Ed. ID:

8/J.13-10

Nickel-Strunz 10th Ed. ID:

9.FB.15

 

9 : SILICATES (Germanates)
F : Tektosilicates without zeolitic H
2O
B : Tektosilicates with additional anions

Related to:

Scapolite Group. Marialite-Meionite Series.

Members of Group:

Scapolite Group: Marialite, Meionite, Silvialite

Varieties:

Marialite, Meionite, Petschite, Wernerite

Synonyms:

Dipyre, Fuscite, Marialite-Meionite Series, Skapolite

 

 

Crystal Data

   

   

Crystallography:

Tetragonal - Dipyramidal

Crystal Habit:

Crystals prismatic, typically with flat pyramidal terminations, striated || [001], to 1.5 m; granular, massive.

Twinning:

None

 

 

Physical Properties

   

 

Cleavage:

Distinct on {100}, Distinct on {110}

Fracture:

Irregular/Uneven to Conchoidal

Tenacity:

Brittle

Moh's Hardness:

5.5 - 6.0

Density:

2.50 - 2.62 (g/cm3)

Luminescence:

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:

Not Radioactive

 

 

Optical Properties

   

   

Color:

Colorless, White, Grey; Pink, Violet, Blue, Yellow, Brown, Orange-Brown; Colorless in thin section.

Transparency:

Transparent, Translucent, Opaque

Luster:

Vitreous, Resinous, Pearly

Refractive Index:

1.539 - 1.541  Uniaxial ( - ) 

Birefringence:

0.007 - 0.009

Dispersion:

Weak to Strong; r > v

Pleochroism:

None

 

 

Occurances

   

   

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.

Common Associations:

Plagioclase, Garnet, Pyroxenes, Amphiboles, Apatite, Titanite, Zircon

Common Impurities:

Fe, Ca, K, S

Type Locality:

Pianura, Phlegrean Fields, Naples Province, Phlegrean Volcanic complex, Campania, Italy

Year Discovered:

Marialite: 1866; Meionite: 1801

View mineral photos:

Scapolite Mineral Photos and Locations

 

 

More Information

   

   

 

Mindat.org (Scapolite)
Webmineral.com (Scapolite)
Mindat.org (Marialite)
Mindat.org (Meionite)
Mindat.org (Petschite)
Mindat.org (Wernerite)
Webmineral.com (Marialite)
Webmineral.com (Meionite)

 

 


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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