Cobble—a rock or mineral fragment that has a diameter between 64 and 256 millimeters (about 2½ and 10 inches).
Conchoidal—a curved [fracture] surface shaped like the inside of a shell or spoon.
Conglomerate—a rock composed of cemented, rounded rock or mineral fragments, most of which are of [gravel] size.
Cretaceous—the third and latest [period] of the [Mesozoic] [Era] (see [p. 3]).
Cryptocrystalline—made up of tiny [crystalline] particles that are too small to be distinguished even under high magnification.
Crystalline—having a definite, orderly internal structure.
Cube—a solid that has six equal, square sides.
Dodecahedron—a solid that has twelve plane, four-sided faces.
Element—a basic building block of all matter, which cannot be separated into different substances by ordinary chemical means.
Eocene—the second [epoch] of the [Tertiary] [Period] (see [p. 3]).