The gray rock in this granite outcrop is a xenolith. What is a xenolith?
Answer:
Xenolith means "foreign rock". As the magma (molten rock) melts its way through the surrounding rock, sometimes a chunk of the surrounding rock breaks away and sinks into the magma. If the magma cools before that chunk melts, it winds up as a xenolith, a chunk of rock that is not part of the igneous rock around it. You can often see these in the polished granite used on buildings.
Non-subscriber
