Zonolite loose fill insulation manufactured by the W.R. GRACE company found in the walls during a residential home inspection. This insulation material was used up until 1980 in homes. Depending on the mining source, this building material was sometimes contaminated with asbestos fibers. Two samples of this material showed no presence of any asbestos contamination. This material is typically seen in the walls and ceilings of residential homes, and was used as concrete block insulation.