How to identify a metal ?
Into a terrain near a very old volcano and a river, my brother found fragments of obsidian of various sizes and colors.
Some of them are "glued" to metallic stones, and some others contain marbles of metals ...
He also found a heavy metallic rocks (encrusted with obsidian) who reacts with magnet, and an other light one (without obsidian) who does not react with magnet.
Do you know a mean to identify those metals ? (I Googled but found nothing very useful so far)
Or do you have a clue of what it could be ?
#1 is a metallic rock encrusted with obsidian. It must be iron because it's heavy, the rust is red, and it reacts to magnet.
#2 and #3 is obsidian with marble of metal who reacts to magnet.
#4 is an unknown (metallic ?) rock. It is light (150 grams for 200 cm3 - 0.33 pounds for 12 cubic inches), of the color of silicon (or the graphite of paper pen !), does not react to magnet but is (electric) conductor with resistance near 0 ohm.