A black pebble snaps to a magnet. That small refusal to behave like an ordinary river stone is often a mineral census: magnetite, an iron oxide with ferrimagnetism, may have survived erosion from igneous bedrock, ore-bearing veins, or industrial debris. The pull is real. It does not, by itself, certify a meteorite.Acid is a sharper interrogator. When a pale stone fizzes under dilute acid, calcite ...More