Roger Weller, geology instructor
firstname.lastname@example.org copyright 2010-R.Weller
Ruby is a variety of the mineral corundum. It is the same chemical, aluminum
oxide, that forms on the surface of aluminum cooking pots and creates a dull
surface. Corundum can come in many colors, but only the red varieties are
Photo is copyright free only for non-commercial educational uses.
Just credit photo to R.Weller/Cochise College.