Rocks are defined as aggregates or mixtures of minerals; rocks also include noncrystalline materials such as the natural glasses, and organic material such as coal. Rocks are found ready-made in nature. They are not homogeneous nor are they crystalline, although they may be made up of crystalline material. The composition...
Revised 1976 and 1985. Reprinted July 1987. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalog