Rhyolite alteration viewed by a Scanning Electron Microscope

Photos from a Scanning Electron Microscope (SEM) showing reacted rhyolite fragments at the end of the laboratory experiments. (a) Image magnified by 500 times showing the rhyolite after it reacted with water at 250 degrees Celsius (482 F). The reacted rhyolite fragments show very little change compared with the unreacted fragments. (b) Image magnified by 300 times showing significant change to the rhyolite fragments after reaction with water at 275 degrees Celsius (527 F). (c) Same as in (b), but the image is magnified by 5000 and small crystals of alteration minerals can be seen. (d) Image magnified by 300 times showing the rhyolite after reaction with water at 325 degrees Celsius (617 F).