SPECIAL PUBLICATION NO. 27


cited using the appropriate chemical formulae (Soper and Osbon, 1922,
pp. 6-7; U.S. Department of Energy, 1979, pp. 5-6; Cameron, 1973,
p. 506). (As noted previously, the formulae cited here are based on a
generalization of the peat-forming process in which peat is derived from
a starting material of cellulose. Due to the complex composition of most
peats, this simplified approximation is not realistic).
 The last criterion in Mason and Berry's definition of a mineral is that of
an ordered atomic arrangement; that is, a mineral should be a crystalline
solid. Mason and Berry (1968) note a group of compounds which are
considered minerals even though the crystalline state is not initially
attained: "A few minerals, the commonest being opal, are formed by the
solidification of a colloidal gel and are noncrystalline initially; many such
minerals become crystalline during geologic time". The mineral opal may
attain an ordered atomic arrangement only in the course of geologic time.
 The coal-forming process is illustrated in Figure 1. As organic matter
(originally deposited as peat) is subjected to conditions of increasing
temperature and pressure it undergoes the changes associated with coal-
ification. The end-product of this process is the mineral graphite (Press
and Siever, 1974, p. 468). Graphite crystallizes in the hexagonal system
and its formula is simply carbon (C). It is found in a number of occur-
rences including metamorphosed coal beds (Quinn and Glass, 1958).
The parallels with the case of opal seem apparent. Neither opal nor peat
initially attain the internal atomic ordering referred to in Mason and Ber-
ry's definition of a mineral. Opal will presumably achieve internal atomic
ordering in the course of geologic time (Mason and Berry, 1968). The
transformation of peat into the mineral graphite requires, in addition to
the passage of time, increases in temperature and pressure (Press and
Siever, 1974) and will be accompanied by the evolution of various liquids
and gases.
 Geologists do not universally include crystalline form as a prerequisite
to classification of a material as a mineral. This is demonstrated in the
continuation of the AGI Glossary's definition of mineral. "Those who
include the requirement of crystalline form in the definition of a mineral
would consider an amorphous compound such as opal to be a 'mineral-
oid' (Gary, et al., eds., 1974)
 The United States Geological Survey in its volume entitled United
States Mineral Resources (Brobst and Pratt, eds., 1973), devotes a chap-
ter to peat as well as chapters to petroleum, natural gas and coal. The
United States Bureau of Mines also considers peat to be a mineral
resource in addition to coals, petroleum and natural gas. These
resources, including peat, are all non-renewable.

 Harvesting or Mining

 Harvesting and mining are both terms which are applied to the extrac-
tion of peat. As was discussed in the section of this report "The Defini-
tion of Peat and Significance of this Definition" the term "harvesting"