In 1973, the TVA requested petrographic examination of several concrete cores from Fontana Dam located in North Carolina to determine whether an alkali-silica reaction had occurred. A petrographic examination was made, and the results of it showed that there was evidence of alkali-silica reaction. While the evidence of reaction was conventional (gel, rims on aggregate particles, cracks), the type of aggregate was not variously described as quartzite or feldspathic muscovite schist or metamorphic subgraywacke and another variety as schist or phyllite, was probably due to the presence of large amounts of strained quartz.
