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.
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!