The term "eye agate" is used categorically to describe a formational event that can occur in any agate. The term is also used generally to describe any concentric circular banding. For example, to cut across a tube formation will reveal consecutive circular banding which may be called an "eye agate" or agate with eyes. Likewise, in Germany betroydal agates were cut with the banding showing concentric circular forms and were called "eye Agates." These examples refer to the general use of the term and not the categorical description that most collectors are familiar with.
The Eye Agate form is a perfect hemisphere or half sphere with concentric banding to the center. All the bands are near perfect circles and are structured like a group of balls one inside the other. The formation is generally small and occurs most often on or near
e covered with eyes, have only one eye, or no eyes. Depending on the agate type the eyes are not always easy to see on the outside surface of the nodule.
s varies greatly. "Eyes" occur in about 5% of Lake Superior agates
the outside surface of an agate nodule. Most eyes are one centimeter or less in diameter. The outside surface of a nodular agate can b
agate nodules and do not seem to occur at all in some other types
The occurrence of "eyes" in various agate type and about 5% in Botswana agates. "Eyes" are quite rare in Brazilian
of agate. The eye formation seems to be more prevalent in smaller a
gate nodules and there is one place in Mexico that produces a small
agate nodules where most of the agates have eyes.