Agate beads and pendants are a banded and or multi-colored member of the quartz family. The characteristic bands of color are caused by the presence of iron and manganese. Agate, one of the oldest known gems has been valued for thousands of years. The most popular types of agate include blue lace agate and moss agate. Agate is reputed to aid insomnia and sweet dreams. Other members of the quartz family include jasper, carnelian and onyx.