RUBYCA Moss Agate Natural Gemstone Beads Moss agate (also called mocha stone) is a semi-precious gemstone formed from silicon dioxide. It is a form of chalcedony which includes minerals of a green colour embedded in the stone, forming filaments and other patterns suggestive of moss. Despite its name, moss agate does not contain organic matter and is usually formed from weathered volcanic rocks.Gemstone Jewelry Care and Cleaning: Gemstones can be cleaned very easily using warm soapy water and a soft brush. Keeping in mind about the stone's hardness and durability, be sure to not use any other objects that are harder than it for scrubbing or cleaning. As with most gemstones, you should not use any household chemicals when caring or cleaning your beads and should avoid any prolonged exposure to extreme of heat as it may cause permanent damage to the gemstone. Your Natural Gemstone Beads should be kept away from other gemstones and jewelry to ensure unnecessary damage or scratching from other harder gemstones.