Sarbossa

Sarbossa, also known as thomsonite, lintonite, comptonite, ozakite, eye stone, or fire rock, was found in small nodules up to one inch (two and a half centimeter) diameter in cavities of rocks formed during volcanic eruptions.

Description
This ornamental stone was fibrous and therefore both tough and soft. It was usually grayish green in color but was sometimes beautifully colored with rings of pink, red, white, and green. A typical stone had a base value of 10 gp.