Types of Agate
Eye agates are most commonly found in agate nodules. ... Shortly after an initial layer of silica is deposited on the walls of the cavity, round droplets of silica gel form on the walls and begin to ... This origin on the inside walls of a cavity explains why eyes are most commonly found in the outer "husk" of an agate nodule.
A unique and rare variety of Fortification Agate from Fairburn, Custer Co., South Dakota, USA.
Agate Geode Gemstone Information. About Agate Geodes - History and Introduction. On the outside, agate geodes appear to be nothing but rock, but looking deeper into the interior of a geode will reveal amazing crystal growth and formations.
Moss Agate . Introduction to Meaning and Uses of Moss Agate. Moss Agate is not banded, and therefore not strictly an Agate in scientific terms; but is included in the Agate family. Agate is a variety of Chalcedony, a mineral of the Quartz family.
Sometimes plume agate inclusions resemble feathers, plants, or flowers. Colors may vary as in sagenite. Dendritic agate has thin, two-dimentional, treelike growths, usually black or dark brown, as is the case with Montana Agate.
Some agates exhibit a shadow effect in which there is what appears to be movement across the agate layers when the specimen is rocked back and forth (or your orientation to the specimen moves). This optical effect only occurs when there are alternating translucent and opaque bands.
Tube Agate During the formation of some agates, parallel projections of tiny hair-thin mineral rods grow first within the silica gel, around which later the chalcedony agate micro-crystals form. In some cases the inclusions remain, but sometimes they weather away leaving hollow tubes that subsequently fill in with silica.
Water-Line Agate (also called water-level or onyx) During its formation, silica-rich solution either entered the cavity slowly laying one band at a time, excess water drained out leaving a small amount of silica to settle out into separate bands, or the vesicle filled under low pressure.