Corundum
Photos Roger Weller, geology instructor
wellerr@cochise.edu copyright 2008-R.Weller
corundum-ruby crystal-1
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
called rubies.

corundum
Photo is copyright free for
non-commercial educational uses.
Just credit photo to R.Weller/Cochise College.