Sarbossa

Sarbossa, also known as thomsonite, lintonite, comptonite, ozakite, eye stone, or fire rock, occurred in small nodules up to 1 in (2.5 cm) in diameter left behind in cavities formed by volcanic activity.

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.

Powers
Adding sarbossa to the material component of spells that morphed the shape of a target object or creature added one to two minutes to the duration of the spell.