Tiger eye agate

Tiger's Eye, also known as Tiger Eye, was a golden member of the agate family with dark brown stripes that exhibited a silky luster called chatoyancy.

Description
In the Realms this ornamental stone was powdered and used as an ingredient in some potions and in the creation of magical markings. Realmslore said that tiger eye agate helped repel spirits and the undead. A typical stone had a base value of 10 gp.