ABSTRACT
Geological material, whether rock, fossil or mineral, is composed ultimately of one or more mineral species. A single, crystalline and generally inorganic phase constitutes what is usually defined as a mineral specimen. The mineral kingdom, however, encompasses a wide variety of naturally occurring substances ranging from native metals to complex organic compounds (Hey, 1962). Rocks and fossils are, for the most part, composed of assemblages of minerals, which may be simple aggregates possessing integrity only through weak cohesive forces between particles or grains (as, for example, clays or lignite), or they may be complex intergrowths of crystalline and amorphous phases possessing great inherent strength (as, for example, granite or mineralized fossil bone). Single minerals, as crystalline, cryptocrystalline or amorphous phases, do however make up a variety of rock types and fossils. Marble and quartzite are well-known examples of single phase or mono-mineralic rocks, and fossils replaced wholly by calcite or pyrite are abundant in sediments.
