Supplemental road log 2: From Lordsburg to Duncan, Arizona, and Steeple Rock district, New Mexico and Arizona
— Virginia T. McLemore

The main objective of this 120-mi road log with 7 stops is to demonstrate how the distribution and timing of the alteration assemblage are related to the formation of precious- and basemetal veins in an epithermal environment. The Steeple Rock district in southwestern New Mexico and southeastern Arizona provides an opportunity to examine this geologic relation. Five distinct types of ore deposits (base metals with gold-silver, gold-silver, copper-silver, fluorite, and manganese) occur in the district, and they appear to be related spatially to two types of alteration assemblages (I) acid-sulfate and (2) neutral pH (alkali-chloride or propylitic- sericitic) {McLemore, 1993a, b; 1996a, b; in press a, b). Furthermore, district-wide variations in both alteration and mineralization also can be studied at Steeple Rock. A secondary purpose of this road log is to tour a historic mining district.