Moss agate is a type of quartz that has distinctive green, mossy inclusions. It is translucent and has a hardness of 6.5 to 7, making it ideal for store jewelry.

The unique pattern of moss agate is formed by the presence of naturally occurring minerals in the stone, such as iron, chromium, or manganese. These minerals form a mossy or fern-like shape and are usually green, but can sometimes include other colors.

The pattern forms as the stone cools and solidifies, with the minerals becoming trapped in the crystal structure of the chalcedony, creating the characteristic "mossy" appearance.