Brian Butts

Presidential Scholars Adviser: Dr. Christopher Kelson

A mineralogical and geochemical investigation of a granitic pegmatite near DeKalb, New York

brian butts picture“Pegmatite” is a textural term that describes an intrusive igneous rock with an extremely coarse-grained texture. Crystals in pegmatites are generally larger than 2cm in size, but examples of much larger crystals are well documented.

A pegmatite of granitic composition known as the McLear Pegmatite - named for its discoverer, J.H. McLear - is found in the Adirondack Lowlands near DeKalb Junction, New York.  It was economically exploited in the early 20th century, when a mine operated by the Green Hill Mining Company extracted feldspar minerals. The ore was shipped by rail to facilities in New Jersey and Rochester, NY where the feldspars were crushed for use in the ceramics industry. The mine is now closed but many questions remain about the origins and chemistry of the McLear pegmatite.

The goal of my Presidential Scholars project is to characterize the mineralogy of the pegmatite, identify mineral phases, and conduct radiogenic isotope analyses (in the Sm-Nd system) in order to identify the source of the parent magma. Previous studies have investigated the chronology of the pegmatite’s emplacement, which I also hope to verify.