Cancrinite
Current inventory:  0 gems
 

  
Cancrinite is named after Count Egor Frantsevich Kankrin (Georg Cancrin) (1774-1845), Russian minister of finance.

Discovered in 1839;   IMA status:  Valid (pre-IMA; Grandfathered)

Chemistry

Chemical Formula:

Na₆Ca₂Al₆Si₆O₂₄(CO₃)₂

Sodium Calcium Aluminum Silicate Carbonate

Molecular Weight:

1,052.50 gm

Composition:

Sodium

13.11 %

Na

17.67 %

Na₂O

Calcium

7.62 %

Ca

10.66 %

CaO

Aluminum

15.38 %

Al

29.06 %

Al₂O₃

Silicon

16.01 %

Si

34.25 %

SiO₂

Carbon

2.28 %

C

8.36 %

CO₂

Oxygen

45.60 %

O

100.00 %

100.00 %

= TOTAL OXIDE

Classification

Mineral Classification:

Silicates (Germanates)

Strunz 8th Ed. ID:

8/J.09-10

Nickel-Strunz 10th Ed. ID:

9.FB.05

9 : SILICATES (Germanates)
F : Tektosilicates without zeolitic H₂O
B : Tektosilicates with additional anions

Related to:

Cancrinite Group.

Members of Group:

Cancrinite Group: Afghanite, Alloriite, Biachellaite, Bystrite, Cancrinite, Cancrisilite, Davyne, Depmeierite, Franzinite, Giusseppeite, Hydroxylcancrinite, Kircherite, Kyanoxilite, Liottite, Marinellite, Microsommite, Pitiglianoite, Quadridavyne, Sacrofanite, Tounkite, Vishnevite

Varieties:

None

Synonyms:

None

Crystal Data

Crystallography:

Hexagonal - Pyramidal

Crystal Habit:

Rarely as prismatic crystals, terminated by a low pyramid, to 2 cm; commonly massive.

Twinning:

Lamellar, rare

Physical Properties

Cleavage:

Perfect on {1010}, Poor on {0001}

Fracture:

Irregular/Uneven

Tenacity:

Brittle

Moh's Hardness:

5.0 - 6.0

Density:

2.42 - 2.51 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Optical Properties

Color:

Colorless, White, light Blue to light Grayish Blue, honey-Yellow, Orange, Reddish; Colorless in thin section

Transparency:

Transparent to Translucent

Luster:

Vitreous, Pearly or Greasy

Refractive Index:

1.495 - 1.528  Uniaxial ( - ) or ( + )

Birefringence:

0.012 - 0.025

Dispersion:

Weak

Pleochroism:

Colorless

Occurances

Geological Setting:

A primary mineral in some alkalic igneous rocks, including pegmatites in nepheline syenites; also as an alteration product of nepheline.

Common Associations:

Nepheline, Sodalite, Natrolite, Orthoclase, Monticellite, Litanian Andradite, Zircon

Common Impurities:

Ti, Fe, Mg, K, Cl, S

Type Locality:

Miass (Miask), Ilmen Mts, Chelyabinsk Oblast', Urals Region, Russia

Year Discovered:

1839

View mineral photos:

Cancrinite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Cancrinite is one of the members of the Feldspathoid group of minerals that includes Cancrinite, Haüyne, Lazurite, Leucite, Nepheline and Sodalite. Minerals with chemistries that are close to those of the alkalai Feldspars, but are poor in silica (SiO2) content, are called Feldspathoids. Although faceted Cancrinite gems are known to exist, they are extemely rare and usually very small. Cabochons are also rare, but more commen than faceted gems. Cabochons with the yellow or orange variety of Cancrinite and contrasting black matrix material makes for a beautiful cabochon, one of the most beautiful of gem cabochons.

Current sources of Cancrinite are Bancroft, Ontario, Canada; Eifel Mountains, Germany; Kola Peninsula, Russia; Alnö, Sweden and Litchfield, Maine, USA.
 

  
Cancrinite gems for sale:

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