CANCRINITE: Bigwood Township, Ontario, Canada (~3 inches across)
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 Value
The International Gem Society (IGS) has a list of businesses offering gemstone appraisal services.
Cancrinite Information
| Data | Value |
| Name | Cancrinite |
| Crystallography | Hexagonal. Crystals prismatic, but rare; usually massive. |
| Colors | Colorless, white, yellow, orange, pink, to reddish, pale blue, bluish gray. |
| Luster | Vitreous; pearly on cleavage; greasy |
| Hardness | 5-6 |
| Density | 2.42-2.51; Vishnevite: 2.3 |
| Birefringence | 0.022 (cancrinite); 0.002-0.012 (vishnevite) |
| Cleavage | Perfect 1 direction. Fracture uneven. Brittle |
| 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. |
| Spectral | Not diagnostic. |
| Formula | (Na,K, Ca)6-8(Al, Si)12O24(CO3,SO4,Cl)1-2 · nH2O. |
OPTICS:
o= 1.507-1.528; e = 1.495 -1.503 (cancrinite)
o= 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; Rumania; Finland; USSR; Korea; China; Zaire; 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.
