"The Aguilar deposit, in northern Argentina, is a hypothermal lead, zinc, silver replacement in Cambrian calcareous quartzite. The rocks had previously been altered to tactite by a granite stock whose contact is from 150 to 250 m. from the ore bodies. The deposit lies between the granite and a post-tactite, pre-mineral fault of some 3,000 m. displacement. The fault provided the ore channel and also prepared favorable areas for later ore deposition by shearing the calcareous and tactite rocks. Both bedded and shear-zone deposits are present. The granite and the mineralization are believed to be of late Tertiary age."