· These definitions are taken from The Readers Digest Great Encyclodepic Dictionary,1966 ·

Rock Geol. The consolidted material forming the essential part of the earths crust, consisting principally of minerals in various stages of aggregation and classified according to mode of formation, as igneous or sedimentry.

min.er.al A naturally occurring, homogeneous substance formed by inorganic processes and having a characteristic set of physical properties, a definite and limited range of chemical composition, and a molecular structure usually expressed in crystalline form.

ag.gre.gate Geol. Composed of distinct minerals seperatable by mechanical means.