Streak test, scratch test.
Look at the pictures from Jim Hemmingway and Cryptic on the TN forum Metal Detecting for Gold and see if your rock looks like the pictures of dendritic silver that they posted on page 3:
http://www.treasurenet.com/forums/m...5463-hit-hard-native-silver-field-trip-3.html
Looks like a sulphide to me. But Hvacker is right; do the tests. To many possibilities to even start guessing.
Streak test is gray ... will have to do Hardness test next, as soon as I research how to do it. Thanks Eu. Ok, did a scratch test on glass... it does scratch glass. Did another test on stainless steel ... it scratches stainless steel as well.
Please be sure to wash your hands afterward Nami if it does, as the garlic smell indicates arsenic, just in case you didn't know. Also a sulfide will have the classic "rotten egg" smell. It is certainly an interesting specimen.Also whack an edge with something. Does it smell like garlic?