19th CENTURY - WORLD WAR I:
New York State’s mining industry achieved its greatest extent during this period. The center of iron mining migrated from the lower Hudson Valley to the Adirondacks although the Mid-Hudson limonite mines and siderite (FeCO3) mines still produced iron ore. At the time of the Civil War, iron from the Adirondacks constituted twenty-five percent of the nation’s production and was critical to the war effort. From stoves to cannons to horseshoes, many essential items were made from in North Country blast furnaces.
Between 1880 and 1918, twenty-three million tons of iron ore worth seventy million dollars were mined statewide, mostly in the Adirondacks. Also in this region, mines for galena for lead, pyrite (FeS2) for sulfur, graphite (C) for pencils, crucibles and electrical components, garnet for abrasive, and talc, used in paint and soap, were established during this period. A single mine in the southern Adirondacks yielded diatomaceous earth, known as Infusorial Earth, which was used for polishing. Emery, a mixture of magnetite, corundum (Al203), and other minerals was mined at Peekskill and used as an abrasive. Quartz, derived from rocks in Ulster and Oneida Counties, was used for glass manufacturing. Molding sand primarily recovered a few inches below the surface of Albany County was used by the iron casting industry.
Granite, sandstone, slate, marble and limestone continued to be mined for construction purposes and mill stones. The type of stone mined, and hence the final product, depended upon the geological formations of each region of the state. Clay was mined statewide for brick, terra cotta, roofing tile and pottery. Small iron mines appeared in hematite (Fe2O3) deposits in central New York State south of the Mohawk valley but these rather quickly were converted to pigment mines, providing the raw material for “barn red” paint. Red and green paint pigment was made from finely ground slate from Washington County.
In central and western New York State, halite (NaCl) and gypsum (CaSO4·2H2O) were mined. Halite (salt) was produced in underground mines and was extracted from brines from specially prepared wells for use as a preservative and in chemical processes. For most of this period, the state of New York controlled a large portion of the salt brine industry. Gypsum, used for fertilizer and plaster, was mined in open cuts. Limestone of a special composition was mined for the raw material for portland cement across the state where it was available.