Tried a vinegar test on a rock from my yard, got a surprise
Found a weird looking rock near the creek last month. Figured I'd try the old vinegar test to see if it was limestone. Poured some on, expected a little fizz. Thing went off like a science fair volcano. Turns out it was a big chunk of calcite, not limestone. Learned that vinegar reacts with any carbonate mineral, not just the rock type I thought. Anyone know a better way to tell calcite from limestone in the field?
Wait you found a chunk of calcite that big just lying around? That's wild. I've only ever seen little bits in rock shops. Your yard must be sitting on some kind of geological jackpot. A piece that reacts that strong is probably super pure. Makes me want to go poke around my own creek now.
Hold up, she's only seen it in rock shops? That's crazy to me. I find little broken pieces of calcite in gravel driveways all the time. The white stuff that fizzes, right? It's not super rare. But a chunk the size of your fist just sitting there, that's a different story.