why do some rocks sparkle and others are just dull and boring
I was hiking last weekend and picked up a rock that had little shiny flecks all through it. Looked almost like glitter but natural. My friend said it was probably mica. Then two feet away I found another rock that was just gray and nothing. Same trail same general area. Why the huge difference? Is it just about what minerals were present when the rock formed or does something else decide which rocks get the sparkle upgrade
Also is there an easy way to tell if shiny flecks are mica versus something like pyrite without licking the rock like a weirdo