DESCRIPTION: Primarily, agate is conspicuously banded chalcedony;  the bands range from parallel to highly uneven, even within some  individual specimens.  Both color and light transmission commonly differ from band to band.  In addition, chalcedony with variously shaped splotchy areas, commonly having arborescent shapes are called agate, usually moss agate.
    The term fossiliferous rock may be applied to any fossil-bearing rock. Those mentioned herein are only a few examples of many that have been used as gemrocks.  Some fossiliferous rocks have been selected for use as gemrocks because of the identities of their contained fossils; others have been chosen because of the patterns their included fossils give when cut in certain directions. The name usually applied to these rocks in the marketplace is the name of the rock preceded by either the name of the predominant fossil (e.g., coraline marble) or the adjective fossiliferous if the rock contains more than one kind of fossil with none predominant (e.g., fossiliferous limestone).  Several other names, however, have been used, most of them based either on the locality from which the rock came or someone's idea of a term that might increase sales of anything made from the rock. Because each of these gemrocks is so-to-speak unique, descriptions, noteworthy localities, etc. are included in the comments given after several of the materials listed under the OTHER NAMES subheading.