6. Pegmatite Pegmatite Extremely coarse grained intrusive Igneous rock. My sample: rounds and oval shaped with small crevasses that showed light colored coarse grained crystallized rocks. Location: Pismo Beach, Ca. My sample was found on the shore line of Pismo Beach. Pismo Beach has a great history behind it, but it dates back to 1886 This is my sample broken up to see the crystallized rock particles on the Inside.