(Click on the picture to return to Rock Type Lab key)
This hand-sized sample really doesn't give you a sense of contorted banding, but the separate colorations are the result of extreme pressure and/or heat application to the original rock. None of the foliations react with hydrochloric acid, but the lighter bandings do get some greenish discoloration.
N. C. Heywood maintains this page, last updated 10NOV99.