Monthly Archives July 2012

Agate

Agate is a variety of silica, belonging to the quartz family, under the chalcedony group. It is not as hard as pure quartz due to the other mineral inclusions in its make-up, and has a hardness of 6.5-7 on the Mohs scale. Agate is often the mineral forming the outer shell of geodes, but this occurs because of the formation of a cavity within their mass. They are common in volcanic rock all over the world, where they fill veins or cracks in the rock. Currently, Brazil, India, and the United States are the main sources of agate in the
Read More