Asbestos is a set of six naturally occurring silicate minerals (e.g. Vermiculite) which were used commercially for their desirable physical properties and for resistance to heat. The asbestos silicate minerals are mined, which according to historical records began more than 4,000 years ago, but did not start large-scale until the end of the 19th century.
Asbestos became increasingly popular among manufacturers and builders in the late 19th century because of its sound absorption, average tensile strength, its resistance to fire, heat, electrical and chemical damage, and affordability. It was used in such applications as electrical insulation for hotplate wiring and in mineral wool building insulation. When asbestos is used for its resistance to fire or heat, the fibers are often mixed with cement (resulting in fiber cement, e.g. "transite" pipe), or woven into fabric or mats and was commonly used in automotive brake linings as well.
In 1913, a mine located six miles from Libby, Montana, was opened and became a primary source of vermiculite. W.R. Grace (a premier specialty chemicals and materials manufacturing company) bought the mine in 1963 and closed it in 1990. In its prime, the mine produced 80 percent of the world's vermiculite. The company still operates smaller vermiculite mines in South Carolina.
When buildings were constructed utilizing a structural steel high-rise framework building codes required specific fire resistance (fire ratings) for the safety of occupants and for the protection of the structural integrity from the high temperatures produced by fire.
One of the constituents mandated by the building code to be incorporated into the fireproofing material for structural steel, wallboard, and many other building products was a mineral known as "Vermiculite." Vermiculite, a mineral similar to mica expands when heated into featherweight pieces that have been used commercially for decades.
Common methods utilized to provide fire resistance (fire ratings) for structural steel is to apply specified thicknesses to the structural steel and decking with a "Spray Applied (Cementitious) Fireproofing" material known as "MONOKOTE™" which was and is to this day manufactured by W.R. Grace & Company.
Since the discovery of health risks associated with asbestos (e.g. "Asbestosis") became known, W.R. Grace removed all asbestos from their products line including Monokote™ which no longer contains asbestos. Subsequently, the Libby mine was closed and asbestos remains the basis for litigation that continues to this day.
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