Get yourself a piece of porclin tile, white, unfinished just like the back of a kitchen or bathroom wall tile. Then scratch it, all minerals , gold, copper, lead, silver, all of them leave a streak. A different colored streak it will help you identify what kind of mineral it is. Then look up the Mohs hardness scale on the computer and follow the directions. That should give you a pretty good idea of what you have. Great find.