Greenstone

Greenstone, was the Realms name of chlorastrolite, a gray-green variety of pumpellyite.

Description
These ornamental stones were soft and usually cut cabochon or tumbled and polished. High quality greenstones could take on a glassy finish, and such stones were sometimes called chlorastras. Greenstones were found in solidified lava flows, in nodules of up to three quarters of an inch (two centimeters) in diameter. Exceptionally large specimens were made into greenstone amulets. Greenstones were plentiful and easy to work with so a fair amount of fraudulent amulets were created and enchanted with Nystul's magical aura. A typical stone had a base value of 10 gp.