This post, based on something I wrote for Helium back in 2011, was first blogged here in 2013. However, it’s a natural tie-in to yesterday’s post about chromium.
The loose gemstone that Alfred the butler described to Master Bruce in The Dark Knight as “a ruby the size of a tangerine” would have been much less interesting had he been talking about “a lump of aluminum oxide with some chromium in it.”
Ruby and Kyanite Locality: Winza, Mpwapwa, Mpwapwa District, Dodoma region, Tanzania Exquisite, lustrous and gemmy ruby crystals in matrix, measuring up to 2 cm, together with small, blue crystals of kyanite. (Photo credit: Wikipedia)