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Petalite
Current inventory:  0 gems
 

Petalite

Chemistry:  LiAlSi4O10  []

Discovered in 1800;   IMA status: Valid (pre-IMA; Grandfathered).
The name Petalite is from the Greek petalos meaning leaf in regard to its perfect basal cleavage. The name for the crystals that Petalite is cut from is Castorite, named after Castor. Castor and
Pollux were heavenly twins and brothers of Helen of Troy from Greek mythology.

 

Classification

   

   

Mineral Classification:

Silicates

Strunz 8th Ed. ID:

8/J.03-10

Nickel-Strunz 10th Ed. ID:

9.EF.05

 

9 : SILICATES (Germanates)
E : Phyllosilicates
F : Single nets with 6-membered rings, connected by M[4], M[8], etc.

Related to:

Petalite - Virgilite Series

 

 

Crystal Data

   

   

Crystallography:

Monoclinic - Prismatic

Crystal Habit:

Crystals tabular on [010], or elongated, to 2 m; some faces may be striated. Commonly foliated cleavable, massive.

Twinning:

Common on [001], lamellar

 

 

Physical Properties

   

 

Cleavage:

[001] Perfect, [201] Imperfect

Fracture:

Imperfectly Conchoidal

Tenacity:

Brittle

Hardness (Mohs):

6.0 - 6.5

Density:

2.412 - 2.422 (g/cm3)

Luminescence:

Thermoluminescent

Radioactivity:

Not Radioactive

 

 

Optical Properties

   

   

Color:

Colorless, White, Gray, Yellow, Pink

Transparency:

Translucent to Transparent

Luster:

Vitreous, Pearly on cleavages

Refractive Index:

1.504 - 1.523  Biaxial ( + )

Birefringence:

0.0120 - 0.0140

Dispersion:

Weak; r > v

Pleochroism:

None

 

 

Occurances

   

   

Geological Setting:

In granite pegmatites, locally constituting an ore of lithium.

Common Associations:

Albite, Spodumene, Lepidolite, Microcline, Pollucite, Quartz, Topaz, Tourmaline

Common Impurities:

Mg,Fe,Na,Ca,K,H2O

Type Locality:

Utö Island, Haninge, Södermanland, Sweden

Year Discovered:

1800

View mineral photos:

Petalite Mineral Photos and Locations

 

 

More Information

   

   

 

Mindat.org
Webmineral.com

 

 


Petalites are beautiful colorless gems which are usually free of inclusions. They are bright white and somewhat rare. Petalite gems could be used in jewelry, but with care since they are a bit brittle. Most gem quality Petalite is currently coming from Brazil.

The name Petalite is from the Greek petalos meaning leaf in regard to its perfect basal cleavage. The name for the crystals that Petalite is cut from is Castorite, named after Castor. Castor and Pollux were heavenly twins and brothers of Helen of Troy from Greek mythology. Pollux is the basis for the naming of Pollucite.

The main sources of gem quality crystals are Paprok, Nuristan Province, Afghanistan; Bahia, Northeast Region, Brazil; Minas Gerais, Southeast Region, Brazil; and Mogok, Sagaing District, Mandalay Division, Burma (Myanmar).
 
 

  
Petalites gems for sale:

We have not photographed our Petalite gems yet.  Please check back soon!
 

 

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