what makes a rock an agate
Agate is a banded form of finely-grained, microcrystalline Quartz. The lovely color patterns and banding make this translucent gemstone very unique. Agates can have many distinctive styles and patterns, but each Agate is unique in its own habit, with no two Agates being the same. Moss Agate is technically not a true Agate as it lacks the banding patterns of Agate. 2  Onyx-Type of Chalcedony gemstone whose meaning can have several connotations. 3  Its most practical gemstone definition describes a solid black Chalcedony, or a banded or layered black and white Chalcedony.