Over the past decades pyrrhotite-containing aggregate has been used in concrete to build basements and foundations in northeastern Connecticut and south-central Massachusetts. The sulphur in the pyrrhotite reacts to several secondary minerals, and associated changes in volume lead to a loss of structural integrity. As a result hundreds of homes have been rendered worthless as remediation costs often exceed the value of the homes and the value of many other homes constructed during the same time period is in question as concrete origin and potential future structural issues are unknown. Trinity College professors Christoph Geiss and Jonathan Gourley have developed a reliable and affordable test for pyrrhotite, and have analyzed over 400 homes in Connecticut and Massachusetts. They will talk about their work and how the results of their ongoing studies may be used in the future to assess pyrrhotite risk to homeowners.