Buchtel College of Arts and Sciences

Date of Last Revision

2024-01-17 10:15:44


Environmental Science

Honors Course

GEOL 497

Number of Credits


Degree Name

Bachelor of Arts

Date of Expected Graduation

Fall 2023


San Diego pegmatites of the Pala and Mesa Grande mining districts are world renowned for their gem-quality minerals and their Li-bearing mineral phases. Pegmatite genesis, especially in San Diego mines, has been a debated topic since the 1900’s (Morgan and London, 2012). Pegmatite genesis is caused by partial melting processes and fractional crystallization that form granitic melts with high concentrations of rare earth elements (REE), such as lithium. Assessing the exact mineralogy and determining the overall textures can provide insight into the crystallization history of pegmatites. In the San Diego pegmatites, lithium-bearing phases, such as lepidolite and pink elbaite (a Na- and Li-rich variety of tourmaline) tend to be early crystallizing phases. Garnet and black schorl tourmaline (Na- and Fe-rich) also appear to crystallize early. Albite (Na-rich feldspar) and muscovite tend to be next in the crystallization sequence, and quartz is the final crystallizing phase and infills any remaining space between the other phases. This crystallization sequence is indicative of a starting melt that is rich in REE, which are removed by crystallization of lepidolite and elbaite, leaving an alkali-rich melt that becomes Si-saturated during the final stages of crystallization. The abundance of Li-bearing minerals in the San Diego pegmatites is important for mining for gemological and lithium resources, which is a pressing societal need given technological reliance on lithium batteries.

Research Sponsor

Molly Witter-Shelleman

First Reader

John Senko

Second Reader

Caleb Holyoke

Honors Faculty Advisor

Caleb Holyoke

Proprietary and/or Confidential Information




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