Click on a letter above to view the list of gems.    

Sogdianite
Current inventory:  1 gem
 

Chemistry:  K_1.5Na_0.5Li_1.8Fe³⁺_0.9Al_0.3ZrSi₁₂O₃₀

Discovered in 1968;   IMA status: Approved (1968).
Sogdianite is named for Sogdiana, an ancient Central Asian state.

Classification

Mineral Classification:

Silicates

Strunz 8th Ed. ID:

8/E.22-120

8 : Silicates
E : Cyclosilicates, triplet rings [Si3O9]6-
22 : Millarite - Osumilite series

Crystal Data

Crystallography:

Hexagonal - Dihexagonal Dipyramidal

Crystal Habit:

Crystals are Tabular, to 1 cm; in platy aggregates, to 15 cm.

Twinning:

None

Physical Properties

Cleavage:

[0001] Perfect

Fracture:

Sub-Conchoidal to Uneven

Tenacity:

Brittle

Moh's Hardness:

5.0 - 7.0 (7.0 if pure)

Density:

2.76 - 2.90 (g/cm³)  (2.90 if pure)

Luminescence:

Fluoresces dark violet under LW UV and very dark red under SW UV.

Radioactivity:

Barely Detectable, GRapi = 79.14 (Gamma Ray American Petroleum Institute Units)

Optical Properties

Color:

Violet

Transparency:

Transparent to Translucent

Luster:

Vitreous to Waxy

Refractive Index:

1.606 - 1.608  Uniaxial ( - )

Birefringence:

0.0020

Dispersion:

n/a

Pleochroism:

None

Occurances

Geological Setting:

In a pegmatite vein with a composition about that of an alkalic granite.

Type Locality:

Dara-i-Pioz Glacier, Alayskiy (Alai) Range, Tien Shan Mts, Districts of the Republican Subordination, Tajikistan

Year Discovered:

1968

More Information

Mindat.org
Webmineral.com

Sogdianite is a extremely rare gem. There are only three know sources: the Dara-i-Pioz massif, Alai Range, Tien Shan, Tajikistan; the Wessels mine, near Kuruman, Cape Province, South Africa; at Washington Pass, Okanogan Co., Washington, USA. Sogdianite is often mixed with other minerals so the specific gravity and hardness are variable. It is closely related to Sugilite.
 

  
Sogdianite gems for sale: