Diamond is the hardest mineral, being a 10 on the Mohs hardness scale. Diamonds are found in igneous rocks called Kimberlites, which are formed deep underground (between 90 and 280 miles below the surface of the Earth). This photo shows cores of kimberlite rock from a drilling event. Rock cores are stored in core boxes for examination.
Volcanic Breccia is a unique extrusive igneous rock that is has large, angular fragments stuck in a fine-grained rock background. This rock forms during an eruption when when rock fragments are plucked off of the inside wall of the volcano and are stuck in the lava, or when rock fragments are picked up from the ground by flowing lava.