MARYLAND GEOLOGICAL SURVEY 223

It is used as a polishing powder and likewise makes an excellent non-
conducting cover for steam pipes; also from its extremely porous
character it has been used for the shipment of dynamite. This mate-
rial was first worked on the Patuxent river in 1882.

The value of the product mined in 1896 was only $3, 500. Much
larger amounts have been obtained in past years.

THE MINERAL WATERS.

The mineral waters of Maryland in the past have not attracted
much attention, but there are several kinds which are being placed
on the market at the present time with greater or less success, and
two at least which are being exported in considerable quantities. A
few are represented as having medicinal properties, but the majority
are sold principally for table waters, mostly in the city of Baltimore.
Nearly all of the well known waters come from the crystalline rocks
of the Piedmont Plateau, only a few being reported up to the present
time from the Appalachian Region and the Coastal Plain. Accord-
ing to the Eleventh Census report, based upon information obtained
in 1890, Maryland ranked thirteenth among the states in the number
of springs reported and twenty-first in the volume of product. The
amount utilized in that year is stated to have had a market value of
$12, 057. Since then several new springs have been placed on the
market, so that the importance of Maryland as a producer of mineral
waters is gradually increasing. In 1896 the value of the output was
$63, 500.

Around many of the springs in the Piedmont region summer
resorts have sprung up, in part as the result of the pure quality of
the water and in part on account of the proximity of the localities
to Baltimore and Washington. Among the more important may be
mentioned the Chattolanee, Strontia, Lystra, Bentley, Takoma and
Carroll Springs. Many other springs are found scattered over the
Piedmont region, but little beyond local use has been made of them
up to the present time.

The springs of the Appalachian Region are not as well known,
although a thermal spring of saline mineral water at Flintstone, Alle-