After spending the last few months primarily researching the historical geology of the rocks, my mentor(s) and I decided that I needed something different to do. Ms. Utterback suggested that I look into the mineralogy of the limestones. One interesting aspect of the Onondaga limestone is that due to its high magnesium content (which gives it its iconic dark grey color) it easily oxidizes. This is why the new dining hall addition onto Kellas looks so much darker than the rest of the stones. When oxygen in the atmosphere reacts with the magnesium present on the surface of the Onondaga limestone blocks it forms magnesium oxide (the same white stuff that is formed when a pure strip of magnesium is burned. This is why the stones in the old part of kellas are lighter and the stones in the addition are darker. In the next few weeks I will have the opportunity to head across the hill to Rensselaer Polytechnic Institute (RPI) to work with some of their professors and lab technicians to perform electron probe microanalysis of oxidized portions of Onondaga limestone, unoxidized portions of Onondaga limestone, and the Bedford Indiana limestone. What is electron probe microanalysis you ask? Let me explain (to the best of my neophytic abilities).
Image from http://ees2.geo.rpi.edu/probe/
Pictured above is the Cameca SX-100 microprobe at RPI that I will be using to analyze my samples. Electron Probe Microanalysis (EPMA) is a way of determining the composition of small areas of mineral specimens. The column in the center of this machine is essentially an electron gun. It "shoots" electrons at a sample encased in a vacuum to prevent interference from common gasses in the air. Around the center tube are a series of different sensors which can collect x-rays and electrons emitted from the sample.
However, to be able to use this machine, the sample needs to be smooth, like smoother than John Travolta in Grease. To do this I need to turn my large sample rocks into small, epoxy mounted, sanded and buffed samples, but there will be more about that in the next post.
-Jess
However, to be able to use this machine, the sample needs to be smooth, like smoother than John Travolta in Grease. To do this I need to turn my large sample rocks into small, epoxy mounted, sanded and buffed samples, but there will be more about that in the next post.
-Jess