226 PHYSIOGRAPHY, GEOLOGY AND MINERAL RESOURCES

some instances with great success. None of these products will prob-
ably give rise in the future to industries of great magnitude, either on
account of the insufficient supply of the material or on account of the
very limited use of the products themselves.

COPPER. —There are three veins of copper ore in Maryland, which
before the opening of the Lake Superior copper region about 1844
and later of the Montana and Arizona mines, were considered of no
mean prominence, and did actually make Maryland for a time one of
the copper-producing states. The first of these veins runs along the
Linganore Hills in Frederick county from New London northward
to a point beyond Libertytown, the ore occurring in slates and lime-
stones. The second vein runs northeast from near Sykesville through
Carroll county to and beyond Finksburg, the ore being found in the
slate. The third deposit is in the Bare Hills in Baltimore county, the
ore occurring in hornblende gneiss. The Maryland copper mines
were probably first opened in the 18th century, but operations ceased
largely on the breaking out of the Revolutionary War and were not
again taken up, to any great extent, until about the year 1835, from
which time for the next few decades considerable ore was produced in
the state.

CHROME. —The chrome industry in Maryland originated in the dis-
covery in 1827 of chrome ore in the serpentine of the Bare Hills in
Baltimore county. Subsequently to that, other deposits were found
associated with the serpentine in Harford and Cecil counties, as well
as at other points in Baltimore county. Between 1828 and 1850
Baltimore supplied most of the chrome ore consumed by the world,
the remainder coming from the serpentine and platinum washings of
the Ural Mountains. After 1850 the foreign demand for Baltimore
ore declined gradually until 1860, since which time almost none has
been shipped abroad. The reason for this was the discovery in 1848
of great deposits of chromite in Asia Minor. This region now sup-
plies largely the world's demand. Since 1886 practically nothing
has been done with the chrome deposits of Maryland, although Bal-
timore is still one of the most prominent centres for chromium salts.