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Afghanite

 

Afghanite

 

Discovered in 1968;   IMA status: Valid (IMA approved 1968)

 

Chemistry

 

 

Chemical Formula:

(Na,Ca,K)8(Si,Al)12O24(SO4,Cl,CO3)3 · H2O

 

Hydrated Sodium Calcium Potassium Aluminum Silicate Carbonate

Molecular Weight:

1,200.45 gm

Composition:

Potassium

2.28 %

K

2.75 %

K2O

 

Sodium

9.19 %

Na

12.39 %

Na2O

 

Calcium

11.69 %

Ca

16.35 %

CaO

 

Aluminum

13.26 %

Al

25.06 %

Al2O3

 

Silicon

14.27 %

Si

30.53 %

SiO2

 

Hydrogen

0.08 %

H

0.75 %

H2O

 

Carbon

0.10 %

C

0.37 %

CO2

 

Sulfur

3.39 %

S

8.47 %

SO3

 

Chlorine

4.58 %

Cl

4.58 %

Cl

 

 

— %

Cl

—1.03 %

—O=Cl2

 

Oxygen

41.16 %

O

 

 

 

 

100.00 %

 

100.00 %

= TOTAL OXIDE

 

 

Classification

   

   

Mineral Classification:

Silicates (Germanates)

Strunz 8th Ed. ID:

8/J.09-50

Nickel-Strunz 10th Ed. ID:

9.FB.05

 

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

Related to:

Cancrinite Group

Members of Group:

Cancrinite Group: Afghanite, Allorite, Biachellaite, Bystrite, Cancrinite, Cancrisilite, Davyne, Depmeierite, Franzinite, Giuseppetite, Hydroxycancrinite, Kircherite, Kyanoxalite, Liottite, Marinellite, Microsommite, Pitiglianoite, Quadridavyne, Sacrofanite, Tounkite, Vishnevite

Varieties:

None

Synonyms:

IMA1967-041

 

 

Crystal Data

   

   

Crystallography:

Hexagonal

Crystal Habit:

As stout to slender, thin tabular laths and as rounded grains or as massive - uniformly indistinguishable crystals forming large masses.

Twinning:

None

 

 

Physical Properties

   

 

Cleavage:

Perfect on [1010]

Fracture:

Conchoidal

Tenacity:

Brittle

Moh's Hardness:

5.5 - 6.0

Density:

2.55 - 2.65 (g/cm3)

Luminescence:

None

Radioactivity:

Barely Detectable; GRapi = 32.54 (Gamma Ray American Petroleum Institute Units)

 

 

Optical Properties

   

   

Color:

Light Blue to Dark Blue, Colorless

Transparency:

Transparent

Luster:

Vitreous

Refractive Index:

1.523 - 1.529  Uniaxial ( + )

Birefringence:

0.006

Dispersion:

n/a

Pleochroism:

None

 

 

Occurances

   

   

Geological Setting:

In thin veinlets cutting lazurite crystals (Sar-e-Sang, Afghanistan); in silicifed limestone xenoliths in pumice (Pitigliano quarry, Italy).

Common Associations:

Lazurite, Sodalite, Nepheline, Phlogopite, Olivine, Diopside, Vesuvianite, Calcite, Pyrite.

Common Impurities:

None

Type Locality:

Lapis-lazuli Mine, Sar-e-Sang, Badakhshan (Badakshan; Badahsan) Province, Afghanistan

Year Discovered:

1968

View mineral photos:

Afghanite Mineral Photos and Locations

 

 

More Information

   

   

 

Mindat.org
Webmineral.com

 

 

Afghanite is is a rare Feldspathoid mineral of the Cancrinite Group of minerals and is found in only a few locations worldwide. It is usually found associated with Lazurite and Sodalite. Crystals are blue to dark blue and usually moderately to heavily included. Gems are typically small and included but beautiful shades of saturated blue. Afghanite was discovered in 1968 in the Lapis-lazuli Mine, Sar-e-Sang, Badakhshan Province, Afghanistan and takes its name from that country.

Afghanite is named after the country of its discovery. It was discovered at the Lapis-lazuli Mine, Sar-e-Sang, Badakhshan Province, Afghanistan.

Locations for Afghanite: at Sar-e-Sang, Badakhshan Province, Afghanistan. In Russia, in the Malaya Bystraya and Tultuy lazurite deposits, near Lake Baikal, and in other unspecified deposits in eastern Siberia. From Lyadzhuar-Darinsk, Pamir Mountains, Tajikistan. In Italy, at the Pitigliano quarry, near Grosseto, Tuscany; on Monte Somma, Campania; from Vetralla and Bassano, Latium. In the Edwards mine, Edwards, St. Lawrence County, New York, USA. At Lake Harbour, Bafin Island, Newfoundland, Canada.

Afghanite gems for sale:

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