Bixbyite,(Mn, Fe)2O3, has been found at five localities in the tin-bearing rhyolite in the Black Range in southwestern New Mexico. It occurs as small cubes implanted with specularite and cassiterite on fissure walls and in cavities and lithophysae with topaz, quartz, specularite, and opal. Two new forms, u{554} and t{421), were found. A review of chemical analyses reported for bixbyite and a new analysis of material from the Black Range substantiates the formula (Mn‴, Fe‴)2O3. This is the third verified occurrence for the mineral.

Pseudobrookite, Fe2O3 · TiO2, occurs in cavities widely distributed throughout the tinbearing rhyolite. Crystals collected from one of the bixbyite localities show six new prism forms, d{560}, f{11.10.0}, g{650}, i{320}, j{830}, and k{410}. This is the third recorded occurrence in the United States.

A review of the occurrences for bixbyite and for pseudobrookite indicates that the minerals have not been found as pyrogenetic accessories. Their origin has been attributed only to fumarolic or pneumatolytic processes. It is reasonable to attribute the origin of these minerals in the tin-bearing rhyolite of the Black Range to vapors escaping from the cooling flows.

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