Libby, Montana, located in the far northwest corner of the state, was founded in the 1860s as a gold-mining town. In 1913, Vermiculite Mountain was discovered in Libby. By 1923, a commercial mining operation was underway, which, at its height, reached a high of 240,000 tons per year-over 50% of all vermiculite mined in the United States. In 1963, when Grace acquired the assets of Zonolite Company, which included the Libby operations, the Company was unaware of any potential health hazards of mining and milling vermiculite. Grace operated the vermiculite mine and processing mill from 1963 until 1990, when the mine was closed. Under Grace ownership, vermiculite production reached 200,000 tons annually and employed up to 200 people. The vermiculite mined near Libby contained a naturally occurring impurity, a form of asbestos known as tremolite, which was largely removed during processing. To ensure the health and safety of Libby employees during the mining and milling process, Grace took a series of actions that included annual x-rays, lung function tests, construction of a wet mill to replace a dry mill, regular air sampling, dust control procedures, improved ventilation and a ban on smoking. Grace also worked closely with the federal government in providing information about health conditions in the Libby mine, cooperating in government studies and complying with all federal standards regarding asbestos exposure. Beginning in 1982, Grace initiated an extensive land reclamation project in Libby. After the mine was closed in 1990, Grace spent several million dollars to remove and control asbestos-containing dust. In 1994 ownership of the site passed to a Montana-based timbering company that met Grace’s requirement for continuity of responsible environmental stewardship. That company had a track record of following Montana’s best management practices for timbering operations.