the deadhorse creek ‘diatreme’ is a proterozoic vent breccia that probably formed in response to early mid-continent rifting. following emplacement of the breccia, the western subcomplex experienced three alteration events, producing the complex mineralogy observed in the main mineralized zone. each event has produced a unique mineral paragenesis and the timing o f each has been deduced from both textural and compositional evidence. while independent, these events made use o f the same pre-existing fracture system along which the western subcomplex is situated. in order, these events were: intrusion o f granitic fluids, alkaline metasomatism, and thermal metamorphism due to the emplacement o f the coldwell alkaline complex. following the alteration events, and presumably a result o f denudation, oxidization and leaching o f the main mineralized zone has produced a supergene paragenesis of: calcite, tyuyamunite, hollandite and barite. the main mineralized zone was enriched in first- and second-row transition metals, rare-earth elements, beryllium, th and u. the mineralization is represented by the presence of: aegirine-jervisite, aegirine-natalyite, barite, baryhte, hollandite, coffinite, hematite, umenorutile, magnetite, monazite-(ce), phenakite, pyrite, rutile, thorite, thorogummite, thortveitite, tyuyamunite, uraninite, v-crichtonite, xenotime-(y), zircon, zircon-thorite-coffinite solid solutions and a few unnamed mineral species. the resulting mineralogy is both unique and complex, with several rare minerals and new compositional extremes reported (i.e., nb-v-rutile, aegirine-jervisite, aegifine-natalyite, zircon-thorite-coffinite solid solutions, dy-xenotdme-(y), thortveitite, baotite, barylite and vcrichtonite). in addition, unique parageneses are reported, giving further insight into the geochemistry o f be, ba, sc, v, n b, ti and cr and conditions of formation of phenakite, baryhte, thortveitite, crichtonite, ilmenorutile, barian feldspars and zircon-thorite-coffinite solid solutions.