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Prismatine
Current inventory:  0 gems
 

  
Prismatine is named for the prismatic form of the crystals.

Discovered in 1886;   IMA status: Valid (IMA approved (redefined) 1996).

Chemistry

Chemical Formula:

(Mg,Al,Fe)₅Al₄(Si,Al)₄(B,Si,Al)(O,OH,F)₂₂

Magnesium Aluminum Iron Boron Silicate Oxide Hydroxide Fluoride

Molecular Weight:

755.83 gm

Composition: 

Classification

Mineral Classification:

Silicates (Germanates)

Strunz 8th Ed. ID:

8/B.31-12

Nickel-Strunz 10th Ed. ID:

9.BJ.50

9 : SILICATES (Germanates)
B : Sorosilicates
J : Sorosilicates with Si₃O₁₀, Si₄O₁₁, etc. anions; cations in octahedral [6] and greater coordination

Related to:

Kornerupine - Prismatine Series, Kornerupine - Harkerite Series

Synonyms:

n/a

Crystal Data

Crystallography:

Orthorhombic - Dipyramidal

Crystal Habit:

Crystals are prismatic.

Twinning:

None

Physical Properties

Cleavage:

[110] Perfect

Tenacity:

Brittle

Moh's Hardness:

6.5 - 7.0

Density:

3.41 - 3.45 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Optical Properties

Color:

Grayish Green, Greenish Brown, Yellowish Brown

Transparency:

Transparent to Translucent

Luster:

Vitreous

Refractive Index:

1.669 - 1.830  Biaxial ( - )

Birefringence:

0.013

Dispersion:

r > v, Strong

Pleochroism:

None

Occurances

Geological Setting:

Metamorphism of boron rich clay sediments to granulite facies.

Type Locality:

Granulite outcrop, Waldheim, Döbeln, Saxony, Germany

Year Discovered:

1886

View mineral photos:

Prismatine Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Prismatine is a member of the Kornerupine-Prismatine series and closely related to Kornerupine. The color is a green that is consistent with Kornerupine but is not pleochroic like Kornerupine. The material from Tanzania has been sold as Kornerupine but after advanced testing by GIA it was determined that it is actually a related analog to Kornerupine known as Prismatine. The green color is largely due to the Vanadium content.

Although there are several locations for finding Prismatine, the only gem quality crystals have been found in Tanzania.
 

  
Prismatine gems for sale:

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