Tell me, Lulu, are there any rules governing which minerals occur together in a rock?! Or can any mineral occur in any rock? Can the mineral composition of a rock provide a clue as to its origin? In short, Lulu, is the mineralogy of rocks orderly or is it all random?!"
"There's both orderliness and there's randomness!"
"Oh great!! No doubt you'll explain?!"
"Oh I will, Lou, I will....!"

© 2001, David J. Leveson