MINERAL HAND SPECIMEN ID USING PHYSICAL PROPERTIES OBSERVED IN HAND SPECIMEN AND BASIC SEM ANALYSIS AS PART OF A 2 YEAR COLLEGE INDEPENDENT STUDY PROJECT

Undergraduates in introductory geology courses at Pasadena City College learn about mineral properties that are useful in identifying individual minerals. Since most introductory geology students have not studied chemistry, our work with minerals stops with the major physical properties; students that continue to take mineralogy at PCC also work with petrographic techniques but have not traditionally had access to analytical equipment to study major element characteristics of mineral unknowns. For the most part, these mineral specimens are out of context, so mineral associations cannot be used to determine varieties. As a geology student with chemistry experience, I wanted to combine hand specimen identification with major element analysis obtained using a scanning electron microscope (Phenom Prox Table top SEM housed in the Chemistry Department at PCC) in order to determine whether these approaches provide additional insight into mineral unknowns and whether their combination might be suitable for other beginning students to combine as part of more regular coursework at PCC.

I worked with 8 unknown mineral specimens which were new to me, using both methods to arrive at a mineral identification. Physical property tests that were introduced in introductory geology course such as cleavage, hardness, luster, streak, etc., were used to narrow down a short list of possible minerals for each specimen. Then I obtained major element analyses of each specimen using the SEM. I used the major element data to rule out possible candidates and conclusively identify the specimens. The physical property tests were highly effective at narrowing the possibilities, so that following up with the SEM was very effective and efficient. Mineral properties were adequate to identify most hand specimens without the SEM data, but several required the SEM data to rule out possible candidates. Further, the SEM data allowed the identification of varieties of certain minerals (e.g. Garnet). As part of this study, I learned about the importance of instrument calibration, specimen preparation and the need for a reliable standard. I plan to continue this work by developing a set of standards for use with our SEM and examining other materials in the instrument.