9 March 2011
A portrait of the feldspar as a young mineral
Posted by Callan Bentley
A few microscope photos for you, showing close-ups of feldspars in igneous dikes in the Crazy Mountains of Montana…
You’ve seen these rocks before, when I posted a few field photos from this area in August 2009. I took these images of feldspar phenocrysts in a hand sample (from a quartz latite dike) with my no-longer-brand-new Nikon microscope camera:
There’s some nice compositional zoning going on in some of these phenocrysts – reflecting the changing composition of the magma in which they nucleated and grew.
Callan Bentley is Associate Professor of Geology at Piedmont Virginia Community College in Charlottesville, Virginia. He is a Fellow of the Geological Society of America. For his work on this blog, the National Association of Geoscience Teachers recognized him with the James Shea Award. He has also won the Outstanding Faculty Award from the State Council on Higher Education in Virginia, and the Biggs Award for Excellence in Geoscience Teaching from the Geoscience Education Division of the Geological Society of America. In previous years, Callan served as a contributing editor at EARTH magazine, President of the Geological Society of Washington and President the Geo2YC division of NAGT.
Dear Callan Bentley, a doubt:
Andesite dikes or Quartz latite dikes?
cool zoning !
Ack! I wrote the post thinking they were andesites, then I looked it up, and I was wrong — they were quartz latites. My fault for not catching the double-appellation!