New Mexico Mineral Symposium — Abstracts

Skarn can be defined as a metamorphic zone developed when igneous rock intrudes carbonate sedimentary rocks. The Victorio Mountains skarn was formed when Montoya Limestone of Ordovician age and other related sedimentary units were intruded by a Tertiary granitic pluton containing large amounts of silicon, aluminum and other elements. The metamorphic rock formed contains calcium and aluminum-rich minerals along with potentially economic amounts of Be-Bi-Mo-W. The Victorio Mountains skarn is located on the south slope of the Middle Hills. This study, excluding the Irish Rose Vein, is concerned with an area of approximately 160 acres which includes the Tungsten Hill mine, Ogre-Bogle mine, Victorio 10 mine, Gulf Oil Victorio Project and other major workings in the area. Drilling conducted by mining companies show the south portion of this skarn slopes gently beneath Quaternary alluvium and continues to the south. Exploration for non-pegmatite sources of beryllium going back as far as the 1950s, reveal the presence of beryllium in the form of helvite occurring in several of the workings. The author, noting the unusual chemistry of the skarn, set out to determine if other beryllium occurrences could be developed within the study area. As a result of extensive sampling and scientific analyses, a list of 35 species has been developed. These include seven localities containing helvite, virtually all major workings, and two localities for beryl (the first of this species to be found entirely within the skarn). Additionally, several species has been added to the Victorio District mineral list, including cotunnite, hydrozincite, perite, rutile and xilingolite. In the opinion of the author the skarn area holds a high potential for the dozen or so beryllium minerals known to occur in skarn deposits world-wide.