Hi guys - I made my first post on the wrong forum, so I'm going to try again. I was poking around in a rock pile with a magnetic tool grabber and found this. It looks like lava with black spots. Can lava be magnetic? Is that what this is? Thanks in advance!
Pumice stone with a high iron content is most likely. If you have any neighbors with lava stone for their yard work run your magnet there You may pick up a few that way too.