The properties of allophane from the South Gardner Mine, Lawrence County, Indiana, are presented. The optical properties indicate that the indices of refraction are a function of the adsorbed water. The differential thermal analyses suggest that the water above 100° C. is structurally held. The x-ray data indicate that allophane has a more ordered structure than glass. The base exchange is high and it is assumed that the base exchange capacity is due to unsatisfied bonds. Its bonding strength is low. Its soil mechanic properties would probably be similar to those of halloysite and its ceramic properties are light burning, high shrinkage, high P.C.E. value, and low plasticity.