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
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...