Scapolite is a sodium calcium aluminum silicate with a complex chemical composition. The name Scapolite represents a series of minerals between Marialite (rich in sodium chloride) and Meionite (rich in calcium carbonate). Distinguishing the scapolite minerals from one another is difficult. They differ only slightly in density and refractive index. With the increase of the calcium content, both density and the refractive index increase.

Scapolite gemstone is transparent. The less transparent material cut as cabachons exhibit the cat’s eye effect. Chatoyancy or chatoyance, is an optical effect seen in some opaque or translucent gemstones. Chatoyancy is caused by the fibrous structure of a material, or by the fibrous inclusions or cavities within the stone. Precipitates of rutile titanium oxide cause chatoyancy. The rutile precipitates are all aligned perpendicularly with respect to cat’s eye effect.

The effect is similar to the sheen off a spool of silk. The luminous streak of reflected light is perpendicular to the fibers. A gemstone cut with the fibers parallel to the base exhibit chatoyancy. Faceted stones are less likely to show the effect well.

Scapolite Cat’s eye stones are rare and valuable since they have exceptionally sharp eyes.Scapolite is found in Canada, the USA, Norway, Italy and Mexico. Gemstone sources are found in Brazil, Madagascar, Tanzania, Kenya, Canada and Burma.