The Mississippian Leadville Formation of Central Colorado is dolomitized near the Sawatch Uplift and hosts numerous Pb-Zn-Ag mineral deposits. Paleomagnetic and rock magnetic data from several dolomite types away from centers of Tertiary intrusive activity imply a late paleozoic (Late Mississippian, ?) age for the dolomitization (e.g., D=148¿, I=-11¿, k=86, &agr;95=8.6¿, N=3 localities, 31 samples in dolomitized units). The magnetization is of diagenetic origin and was probably acquired during or soon after dolomitization. Tertiary thermochemical activity has overprinted dolomites close to intrusive centers. Data indicate that limestones removed from igneous activity were also remagnetized at the same time.