Figure 4. Thin beds of schist in the Waterville Formation. On the right side are thin layers rich in quartz. On the left side are layers rich in mica minerals. The light colored spots in the rock on the left are clots of the metamorphic mineral sillimanite which grew when the rocks of this area were heated to very high temperatures hundreds of millions of years ago. Note the acorn cap for scale.
Last updated on July 5, 2007