MARYLAND GEOLOGICAL SURVEY 205

MINERAL RESOURCES.

GENERAL STATEMENT.

The geological formations which have been described in the pre-
ceding pages afford a great variety of mineral products, some of which
are mined to-day with profit and are susceptible of further develop-
ment; others which have in the past been successfully employed, but
are not at the present time worked, although the commercial condi-
tions may be such as to again render them of economic value; and
still others which are known to occur, but have not yet been found in
sufficient quantities to warrant their exploitation.

The location and distribution of each of these mineral products is
determined by the geological formation in which it is found, the
limits of the formation. representing at the same time the boundaries
within which the particular economic product may be anticipated.
Many mineral products, to be sure, may be restricted to certain por-
tions of a particular formation, or in some instances may be found in
more than one such geological division. Still geological maps are
recognized to-day as of much importance by those who are intelligently
developing our resources, and are regarded as a valuable guide in
determining the distribution of the economic deposits. The futility
of attempting to develop mineral substances in a formation which
has been shown by careful geological investigation to be devoid of
them is also clearly recognized, and in this way large sums of money,
which might otherwise be lost in fruitless enterprises, are saved.

The distribution of the mineral resources of Maryland may be best
understood by reference to the geological map. In the crystalline
rocks of the Piedmont region, between the Monocacy and the Chesa-
peake, we find the most varied, if not the most valuable list. Here
occur the most important building stones: the slates of Delta and
Ijamsville; the granites of Port Deposit, Woodstock and Guilford;
the gneiss of Baltimore; the marble of Cockeysville and Texas; the
sandstone of Deer Creek; and the serpentine of Broad Creek and
Bare Hills. In these oldest rocks occur also the ores of gold, copper,
chrome, lead and zinc. Much of the best iron ore also belongs here,