I posted this over in the meteorite forum, but after some research I wonder if the mystery rock I found is Limonite. I found this at a Fort Lauderdale beach yesterday, pretty far away from the water at a volleyball court. It was about 10 inches down in the sand, and my PI metal detector locked on to this pretty easily. I have a Pro Find 35 pinpointer, which makes a different sound for ferrous items, which it does on this rock. It weighs about 76 grams, seems unusually heavy for its size, and a magnet does stick to it. Before I send it anywhere for analysis, I was wondering if anyone here might have any thoughts? Possible Limonite?