furiouskitten: Because I can, have more photomicrographs. …


Because I can, have more photomicrographs.  These are all from thin sections I’ve made from columnar rhyolite from Hughes Mountain, MO in the St. Francois Mountains (of southeast MO).

These rocks are roughly 1.5 billion years old and display prominent phenocrysts (larger crystals in the smaller groundmass), flow banding, and fiamme (crushed pumice) in hand sample.  Microscopically, the flow banding is shown to wrap around the phenocrysts, which are mainly plagioclase (classified due to observed albite twinning), and the fiamme have been texturally altered.

Geology Nerd

This entry was posted in Beautiful Minerals and tagged , , , . Bookmark the permalink.

Leave a Reply