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White Scapolite Crystal Grouping

The Mineral scapolite




Scapolite is a mineral series consisting of two very similar minerals: sodium-rich Marialite and calcium-rich Meionite. The two Scapolites also differ in that Meionite has a carbonate radical in place of chlorine that is present in Marialite. The two Scapolite minerals are often visibly indistinguishable from each other, and they also form unclassified intermediary examples within their series. Scapolite is the accepted term that encompasses both minerals, and further classification into Marialite or Meionite is often not done unless the species determination is absolute.

Scapolite forms as an alteration mineral of the feldspars. It can form in two entirely different and unrelated habits, as large and stocky white, opaque crystals, and as prismatic, completely transparent gemmy crystals in elongated form.

For additional information, see the gemstone section on Scapolite.
Chemical Formula Marialite: Na4(Al3Si9O24)Cl
Meionite:
Ca4(Al6Si9O24)(CO3)
Composition Marialite: Sodium aluminum chloro-silicate
Meionite
:
Calcium aluminum carbonate-silicate
Within the series, sodium and calcium are fully interchangeable. The chlorine and carbonate are also interchangeable, and are occasionally replaced partially with a sulfate radical.
Variable Formula (Na,Ca)4(Al,Si)3Si6O24)(Cl,CO3,SO4)
Color White, gray, colorless, cream, yellow, bluish-gray, and purple. Less commonly blue, brown, green, red, and pink.
Streak White
Hardness 5 - 6
Crystal System Tetragonal
3D Crystal Atlas
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Crystal Forms
and Aggregates
Crystals are often short and stout with a slightly angled or pyramidal termination, or long and prismatic. Crystals can be very large and fat, and are often intergrown in groups of such crystals or are columnar. Also grainy, massive, and crudely as formed crystal masses. Prismatic crystals are often striated.
Transparency Transparent to opaque
Specific Gravity 2.5 - 2.8
Luster Vitreous to dull
Cleavage 2,2
Fracture Conchoidal, uneven
Tenacity Brittle
Other ID Marks Often fluorescent, sometimes brightly. Colors include white, yellow, and pink. Fluorescence may be present both in shortwave and longwave.
In Group Silicates; Tectosilicates
Striking Features Crystal habit, environment, and fluorescence.
Environment Chiefly in metamorphic rocks, such as metamorphosed limestones, skarns, gneisses, and hornfels. Also in granite pegmatites and volcanic rocks such as basalt.
Rock Type Igneous, Metamorphic
Popularity (1-4) 2
Prevalence (1-3) 1
Demand (1-3) 2


Scapolite AUCTIONS

VARIETIES
 -  Variety of Scapolite with a gray color (and possibly a tint of purple or blue) with slight chatoyancy.
 -  Trade name for purple Scapolite from Tanzania.
 -  A variety or synonym of Scapolite. This term is often used to describe a strongly fluorescent form of Scapolite, especially the greenish-gray to material described from Quebec, Canada. The term Wernertite may also be used to describe an intermediary member between Marialite and Meionite.


USES
The gemmy clear crystals of Scapolite are important collector minerals, especially when they exhibit a good size and color. These transparent forms are also cut as rare collectors gemstones.

NOTEWORTHY LOCALITIES
Although Scapolite is fairly common mineral, several localities stand out for producing excellent specimens of gemmy, transparent examples of this mineral. Beautiful purple crystals come from Afghanistan at Badakhshan Province; and at Dara-i-Pech, Konar Province. Light purple Scapolite comes from Muzeinaya, Kukh-i-Lal, Tajikistan; and pale yellow crystals from Karur, Tamil Nadu, India.

Colorless and yellow Scapolite is found in the marble region of  Mogok, Burma (Myanmar), and transparent yellows crystals come from Tanzania in the Merelani Hills, Arusha; and in  Morogoro, Uruguru. Transparent, light yellow crystals come from Antananarivo and Tuléar Provinces, Madagascar; and colorless, elongated crystals from Linópolis, Doce valley, Minas Gerais, Brazil.

In the U.S., fairly large white Scapolite crystals have come from Franklin, Sussex Co., New Jersey; Amity and Twin Lakes in Woodbury, Orange Co., New York; and Pierrepont and Rossie, St. Lawrence Co., New York. In Canada, excellent crystals come from the Bancroft area, Ontario; and from Diamond Lake, Herschel Township, Ontario. Good Scapolite was found in Gooderham, Haliburton Co., Ontario; and a strongly fluorescent Scapolite with a bright yellow fluorescence, comes from Grenville-sur-la-Rouge, Québec, associated with blue-fluorescing Diopside.

COMMON MINERAL ASSOCIATIONS
Diopside, Biotite, Phlogopite, Titanite, Hornblende, Actinolite, Almandine, Microcline, Muscovite

DISTINGUISHING SIMILAR MINERALS
Feldspars - Often form in different crystal habits, lacks fluorescence.
Nepheline - Different cleavage, lacks fluorescence.


scapolite PHOTOS
 
ADDITIONAL RESOURCES
 
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