Tin deposits in the Black Range district
— Charles H. Maxwell, Eugene E. Foord, Mariel R. Oakman, and D. B. Harvey

The Black Range tin district is in the eastern part of the Datil—Mogollon volcanic field, in Catron and Sierra Counties, southwestern New Mexico. Host for the tin deposits is the Oligocene Taylor Creek Rhyolite and associated pyroclastic rocks. The high-silica, I-type rhyolite is peraluminous, moderately evolved, contains about 1% normative corundum, and normative albite plus anorthite about equal to orthoclase. The rhyolite is porphyritic, with sanidine and quartz phenocrysts. Tin was deposited in a near-surface volcanic environment characterized by extreme temperature and pressure gradients. Conditions of tin deposition were variable from locality to locality, ranging from high-temperature, vapor-dominated systems to low-temperature and pressure, fluid-dominated systems. Cassiterite occurs in lithophysae and miarolitic cavities, in gash veins and veinlets, in veins and stockworks of reticulate veinlets, and disseminated in altered rock. The most abundant form of cassiterite is wood-tin. Nearly as abundant is dark-red cassiterite, pseudomorphic after hematite, and in bladed aggregates intergrown with hematite. Less common are euhedral crystals or aggregates of crystals. The cassiterite  varies from essentially pure SnO₂ to material with as much as 10 wt% of Fe, Sb, As, Zn, In, Si, and other elements. Commonly associated minerals include hematite, pseudobrookite, bixbyite, topaz, sanidine, clinopyroxene , durangite , beudandite , hidalgoite, jarosite , alunite , heuIandite , cristobalite , tridymite , quartz, chalcedony, opal, fluorite, cryptomelane, smectite, todorokite, and varlamoffite. Very sparse amounts of several new antimonates, arsenates, and fluoroarsenates occur at at least one locality. Almost all of the tin produced in the district was wood-tin nuggets from placer or colluvial deposits. A small proportion of the tin apparently was derived from flow domes, but the majority most likely came from conduit and underlying intrusives. Deuteric fluids from these intrusives may have interacted to varying extent with meteoric ground water. Some of the wood-tin is of supergene origin.