well, and they're quite brittle. all those nice clean cleavage planes mean that a nice good smack on a refrigerator and... you have tons of incredibly hard unscratchable microdiamonds... (they're high pressure materils. without the high pressure of the deep crust around they don't hold together too well... but it does make them very dense and hard.) i'd take a nice topaz over them shiny glassy things any day.
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i'd take a nice topaz over them shiny glassy things any day.