January Microphoto of the Month
Rotated Crystal in Fault Zone
This crystal of the mineral hornblende is within a zone of movement called a fault. During faulting, rock on one side of the fault moves with respect to rock on the other side of the fault. Once in a while, a crystal gets trapped in the movement zone and rotates. In this case, we can tell from the rotation that rock at the top part of the slide moved to the left with respect to the rock at the bottom.