Moss agate, also known as mocha stone, is a gemstone renowned for the greenish filaments that seem to resemble creeping moss or other vegetation. The alternative name comes from the Arabian city of Mocha in Yemen, which was an ancient source for the gemstone. There is some disagreement as to the interchangeability of these gemstone names though. Some argue mocha stone should be reserved for specific moss agate with brown or red coloring.
Moss agate, like most gemstones, has long been used for personal ornamentation. During the late 18th century, moss agate was widely regarded as a good luck stone in Britain. Due to the inclusions resembling moss or ferns, moss agate was also viewed as a stone of agriculture amongst gardeners and farmers. It's said European farmers once used to hang moss agate from trees and around the horns of oxen when plowing to encourage successful harvests.
