USING SCANNING ELECTRON MICROSCOPY TO CATALOG MINERALS FROM THE TRANS-PECOS MAGMATIC PROVINCE

The purpose of this project is to develop standard operating procedures for a database of rocks and minerals from the Trans Pecos Magmatic Province (TPMP). The database will contain hand samples, thin sections, site location descriptions using global positioning system (GPS) coordinates, chemical composition, and other petrologic and mineralogic data. Most notable is the inclusion of scanning electron microscopy (SEM) derived data, a major focus of this project.

To initiate this project, samples were collected from the Crossen formation at Hancock Hill, Alpine, Texas. Two thin sections were analyzed using scanning electron microscopy-energy dispersive spectroscopy (EDS) to reveal mass per cent oxides. EDS analysis was performed to determine An-Ab-Or content of the feldspars. Preliminary data reveal that the feldspars average in the range of Or_35-50 (anorthoclase/sanidine). Points of interest, such as vesicles, dissolution features, secondary minerals, and magmatic minerals were sought out to help define and describe the samples. Data for iron oxides are being interpreted.