Cancrinite Value, Price, and Jewelry Information

CANCRINITE: Bigwood Township, Ontario, Canada (~3 inches across). Photo © Joel E. Arem, PhD, FGA. Used with permission.

Cancrinite

Cancrinite is one of the most attractive of all opaque or translucent gem materials. It is a bit too soft for average wear, but its distinctive color is worthy of jewelry. Cancrinite may be tricky to cut because it often contains numerous hard inclusions. Faceted gems even as small as 1 carat are considered great rarities.

Cancrinite Information

Data Value
Name Cancrinite
Colors Colorless, white, yellow, orange, pink, to reddish, pale blue, bluish gray.
Crystallography Hexagonal. Crystals prismatic, but rare; usually massive.
Refractive Index 1.488-1.528
Luster Vitreous; pearly on cleavage; greasy
Hardness 5 - 6
Fracture Uneven
Specific Gravity 2.42-2.51; Vishnevite: 2.3.
Birefringence 0.022 (cancrinite); 0.002-0.012 (vishnevite).
Cleavage Perfect 1 direction
Dispersion Weak
Stone Sizes Masses occur up to several pounds, but Cancrinite is usually in veins a few inches across. It is usually cut as cabochons and beads. The Canadian material is orangy yellow in color, with a greasy luster. Faceted stones are exceedingly rare and always less than 1-2 carats.
Luminescence None in UV. X-ray orange-yellow.
Luminescence Present Yes
Luminescence Type X-ray Colors
Transparency Translucent to opaque.
Absorption Spectrum Not diagnostic.
Formula

(Na,K, Ca)6-8(Al, Si)12O24(CO3,SO4,Cl)1-2 · nH2O.

Optics

= 1.507-1.528; e = 1.495 -1.503 (cancrinite).

= 1.490-1.507; e = 1.488 -1.495 (vishnevite).

Uniaxial (-), chlorine-rich variety (microsommite) is optically (+)

Optic Sign Uniaxial +, Uniaxial -

OPTICS:

= 1.507-1.528; e = 1.495 -1.503 (cancrinite)

= 1.490-1.507; e = 1.488 -1.495 (vishnevite)

Uniaxial (-), chlorine-rich variety (microsommite) is optically (+)

OCCURRENCE: Primarily in alkali-rich rocks; also as an alternation product of nepheline.

Iron Hill, Colorado; Kennebec County, Maine

Norway; Romania; Finland; Russia; North Korea; China; Democratic Republic of the Congo; India; Uganda; Kenya.

Bancroft District, Ontario, Canada: fine gemmy material.

COMMENTS: Cancrinite is one of the most attractive of all opaque or translucent gem materials. It is a bit too soft for average wear, but its distinctive color is worthy of jewelry. Cancrinite may be tricky to cut because it often contains numerous hard inclusions. Faceted gems even as small as 1 carat are considered great rarities.

NAME:  After Count Cancrin, Finance Minister of Russia.