Mykaro

Mykaro, also known as smithsonite, was a massive gemstone found in many hues (yellow, straw yellow, pale brown, reddish brown, green, blue, blue-green), as crystals or as crusts up to 2 in (5 cm) thick in rock cavities.

Description
These semi-precious stones were soft and tough when found as a crust, but brittle in crystal form. It was usually cut cabochon, particularly if it was patterned with thick bands of varying colors, but was sometimes faceted. A typical specimen had a base value of 50 gp.