Brazilian Agate slices, wholesale, bulk, and retail ( Agate slice with drilled hole or NO drilled hole ) Many different agate varieties exist such as..eye agate, scenic agate, dendritic agate, and moss agate. Agate geodes are formed in volcanic lava which contain gas bubbles that fill with water and turn to quartz. Agate is quartz with impurities Mostly translucent. 7 on Mohs hardness.The natural color of agate is called natural - mostly gray, red brown (All other colors are dyed colors.) Size is by longest points. Agates form in many shapes.