Limestone.
Metamorphic limestones exist in the valley of James River, between
Richmond and Lynchburg. Silurian limestone extends from the Potomac
to Tennessee, in great variety. Since the discovery that building lime
with a large percentage of the carbonate of magnesia, is a poor material to
use in the mortar of large buildings and other permanent works of
masonry and brick, peculiar value attaches to beds of pure carbonate of
lime. Such beds fortunately exist at convenient localities in the great
Shenandoah Valley, and lime-burning is already carried on there at two
points—Riverton, in Warren County, and Eagle Rock, in Botetourt—
where an article is produced entirely free from magnesia, and is in great
demand for city work, where the sulphurous fumes of coal combustion are
so destructive to magnesian-lime mortar. As this pure limestone exists in
many places, the industry is a rapidly-growing and a profitable one.
Most excellent hydraulic cement has been produced for many years
and in large quantity, at Balcony Falls, in Rockbridge County. The stone
is also found in Bedford, near Buford's Gap, but has not been utilized
until recently.
All the various limestones, from the most common building-rock to
the finest marble, are found in Virginia. Her dolamite limestone has been
found so superior for fluxing certain iron ores, that it has been carried
considerable distances by rail, in preference to using common limestone on
the ground. Virginia may be said to be an agricultural lime State.
The whole Valley has the best limestone for burning. The whole of
Tidewater has shell (carbonate) marl. A good vein of limestone runs
across Upper, Middle and Lower Piedmont. Several of the carbonate
marls, mixed with clay, will, by being calcined, make cement like the
Portland that is made in England. The travertine marl of the Valley,
and the highly aluminous clays of that section, should make such cements
very cheaply.
