Moss agate isn't actually moss or technically an agate. It is a variety of chalcedony, belonging to the quartz family. The spreading moss-like dendritic inclusions you see in moss agate are mostly oxides of manganese or iron.
Tai Chi Stone, also known as Tai Chi Quartz, Taiji Jade, and Ying Yang Jade, is a variety of white Quartz and black jasper that crystallizes together in mass formation. They can appear in a more banded scheme similar to Zebra Jasper, or when carved into smaller pieces, very symmetrical in color, resembling a yin-yang color pattern. This is a relatively new crystal on the market that has only been recently discovered in China, with no other localities anywhere in the world.
