This is just plain weird - a triangular mineral crystal. Newberyite is a rare magnesium phosphate, found first in a series of lava caves in Australia, the type locality. It does not normally form good or large crystals, but this is an exception, as it has replaced an idiomorphic crystal of the mineral struvite in this weird environment near Death Valley in California. The crystal is complete all around. I have never seen another like it, and can find only one reference (on MINDAT) of a similar crystal. If I had to guess, it is the kind of thing that a lucky California field collector found once upon a time - certainly not recently. From the noted pseudomorph collection of Dr Wouter van Tichelen of Belgium.