Asbestos a naturally-occurring mineral that is unique for its fire-retardant qualities. The word itself derives from the Greek word for inextinguishable. Asbestosis a form of pneumoconiosis in which scarring (fibrosis) occurs. A disease of the lungs that may lead to shortness of breath caused by inhaling asbestos fibers. Dry Mill a mill that processes ore using various mechanical means without the use of water or other liquids. Before 1954, the milling process at Libby was with a dry mill. A second mill, operating a wet process, was added in 1955 to accomplish the first steps of separation. In 1974, the existing dry and wet mills were shut down and ore was processed in a new mill built nearby, operating on an entirely wet process. f/cc fibers greater than 5 microns in length per cubic centimeter of air. When using the membrane filter method of air sampling for asbestos, results are reported as f/cc. fy fiber year. A fiber year is a unit of measurement equivalent to exposure to one asbestos fiber for one year. (Level of exposure in f/cc multiplied by the length of time of exposure in years or fraction thereof.) Lung Function Test a medical test offered to determine lung capabilities. Mesothelioma a rare cancer of the chest and abdominal cavity linings. Monokote® Fireproofing a Grace product once formulated with vermiculite that was sprayed on structural steel in buildings for fire protection and insulation. Monokote is today an asbestos-free product that continues to provide superior fire resistance for structural steel. Morbidity the rate of disease or proportion of diseased persons in a given locality or group of persons. Mortality the proportion of deaths of the population of a region or group; death rate. Opacities scarring or fibrosis of the lungs, detectable by x-rays. Pleural Effusion a secretion of liquid which may collect between the outside of the lung and the pleural sac. Pleural Calcification changes in the pleura or sac that encloses the lungs. Tremolite a common contaminant of mined materials, which may occur in fibrous or non-fibrous form. It occurs in vermiculite in both asbestos and non-asbestos form. Vermiculite a mineral formed millions of years ago by the natural alterations of mica. When heated, it expands up to 15 times in volume, making it useful in manufacturing, construction and agriculture. Wet Mill a mill that processes ore through an entirely wet process. In many operations it is considered the safest procedure because it produces the least dust. The new Libby wet mill opened in 1974, although a wet mill process had been used since 1955 to accomplish the first stages of separation. The separation was made using vibrating screens, roll screens, Humphrey separators and flotation. The concentrate was then dewatered, dried and hauled to the screening plant.