You can easily check to see if it is calcite or quartz. Get some type of diluted acid, like diluted hydrochloric acid. Drip a little on a clean sample. If it fizzes, it is most likely calcite. If it doe not fizz, it is probably quartz. The quarries up in the Ohio/Michigan border area are full of calcite crystals. Way back in my college days, we made several trips up to a Toledo area quarry to collect calcite crystals. They formed in pockets in the limestone.