BUREAU OF GEOLOGY


 A standard mineralogy textbook for university students, Elements of
 Mineralogy (Mason and Berry, 1968), gives the following definition of a
 mineral: "A mineral is a naturally occurring, homogeneous solid, inorgan-
 ically formed, with a definite chemical composition and an ordered
 atomic arrangement". This definition is useful because its authors con-
 tinue by expanding on each part of their definition, taking into account
 the complexity of the group of compounds classified as minerals.
 According to this definition, a mineral must be naturally occurring. This
 eliminates materials which are synthesized in the laboratory or are
 formed as by-products of various manufacturing processes. Since peat is
 indisputably naturally occurring, this aspect of the definition will not be
 considered further.
 A mineral must also be a homogeneous solid. This qualification elimi-
 nates liquids and gases from consideration and implies that a mineral
 cannot be separated into simpler compounds by any physical means
 (Mason and Berry, 1968). In the coalification process by which plant
 material (i.e., cellulose) becomes peat, water, carbon dioxide and meth-
 ane are evolved with time (U.S. Department of Energy, 1979). The coali-
 fication process (U.S. Department of Energy, 1979) refers to a general-
 ization of the peat-forming process in which all initial plant material is
 referred to as cellulose. In actuality, peat contains many types of plant
 material and may possibly contain no cellulose at all. It is important here
 to note that many mineral substances evolve water or gaseous by-
 products when subjected to changed conditions of pressure or tempera-
 ture. Gypsum dehydrates (evolves water) forming anhydrite. The mineral
 talc evolves water and forms enstatite and quartz at elevated tempera-
 tures. Thus, minerals may contain water as an integral part of their crys-
 tal structures.
 The term mineral is restricted by definition (Mason and Berry, 1968) to
 refer to inorganically formed substances. It eliminates homogeneous
 solids formed by plants and animals such as oyster shells, pearls and
 gallstones. Ostensibly, this qualification could eliminate peat from con-
 sideration.
 The American Geological Institute in its Glossary of Geology (Gary, et
 al., eds., 1974) includes the following references in its definition of the
 term mineral: "A mineral is generally considered to be inorganic, though
 organic compounds are classified by some as minerals". Thus, organic
 compounds are not automatically eliminated from consideration as min-
 erals. This suggests that the term mineral has come to be used in a sense
 that is less restricted than might be supposed from examination of the
 definition presented to beginning students of mineralogy.
 Minerals are defined as having definite chemical composition (Mason
 and Berry, 1968). This implies that their composition must be readily
 expressible using a chemical formula. It does not preclude variation in
 chemical composition. Variation within definite limits is allowed, thus,
the composition is definite but not fixed (Mason and Berry, 1968). The
compositions of cellulose and the peat derived from it are frequently