A pyrometasomatic magnetite-hematite deposit in sedimentary rocks of Permian age near the margin of the Lone Mountain stock in Lincoln County, N. Mex., contains between 0.015 percent and 0.031 percent uranium. The deposit is composed mainly of magnetite with lesser amounts of hematite, hydrated iron oxides, pyrite, leuchtenbergite(?), gypsum, chalcopyrite, metatorbernite, torbernite(?), covellite, sphalerite(?), quartz, marcasite, and an unidentified uranium-bearing mineral; it is surrounded by an aureole of recrystallized limestone, gypsum, epidote, and actinolite with lesser amounts of specularite, phlogopite, fluorite, pyrite, and chalcopyrite. Autoradiographs and polished section studies suggest that most of the uranium is dispersed in the iron oxide minerals. The association of iron and uranium may be related to the melting points of the elements. The deposit probably formed at a rather low temperature by self-oxidation of a ferrous hydroxide hydrosol contained in a mildly alkaline solution.

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