CRUMBLING FOUNDATIONS: Upwards of 35,000 homes in parts of the northern and eastern sections of Connecticut are facing a potentially devastating issue due to the presence of a naturally occurring iron sulfide originating from a quarry in Willington. The mineral-pyrrhotite-causes the slow deterioration of concrete foundations when it's exposed to oxygen and water. While the presence of pyrrhotite indicates the potential for concrete deterioration, its existence alone does not necessarily cause it. Homes and structures in approximately 36 towns may be affected by what appears to be a slow moving natural disaster. As a structure continues to deteriorate, it often becomes unsound. Cracking, flaking, bowing, and separation of the concrete has already appeared in many residential developments, including condominiums and Plan Unit Developments, built between 1983 and 2011.