EXAMINING ELEMENTAL ANALYSIS AND INCLUSIONS OF EMERALD AND RED BERYL FROM THE CRABTREE PEGMATITE AND WAH WAH MOUNTAINS USING THE SCANNING ELECTRON MICROSCOPE

Within the United States two interesting and valuable occurrences of beryl are emerald from the Crabtree Mine of North Carolina and the very rare red beryl occurring in topaz rhyolite from Utah. A complex emerald-bearing pegmatite from the Crabtree Mine near Spruce Pine, North Carolina is currently being analyzed in detail along with a red beryl rhyolite from the Wah Wah Mountain Range in Utah. The purpose of this research is to observe the correlation of inclusions and elemental composition between the two minerals. Examination of hand samples from the Crabtree Mine indicates euhedral to anhedral emerald crystals with accessory minerals such as tourmaline, biotite, garnet, and pyrite in a plagioclase, potassium feldspar, and quartz matrix. The emeralds are concentrated along the border zone near the contact of the pegmatite where the country rock has been altered to biotite ± tourmaline. The emeralds also exhibit color zoning with darker, rich colors toward the middle and visible inclusions throughout various crystals. The tourmaline present along the contact zone is also euhedral and varies in size. The rhyolitic hand samples contain red beryl crystals which are euhedral and high in clarity. Polished thin sections of rock samples and mounted crystals show inclusions throughout the emeralds which are more abundant in the Spruce Pine samples than the red beryl from the Wah Wah Mountains. Scanning electron microscopy (SEM) is used to complete elemental mapping of polished thin sections. Zoning throughout crystals is also analyzed using a rim to core traverse. Inclusions are studied in more detail and are common in emerald, feldspar, and red beryl. The next step of our research will include continuing SEM analysis of detailed elemental composition, specific mineral phases, and the distribution of mineral inclusions in order to compare the emeralds and red beryls from the two locations.