Picture is kind of hard to see in any detail but with the assumption that this is not a hunk of limestone...
They have metal detectors that will find gold as small as a single fleck in a sample (got one)... Based on what I have seen though dubious, I have better quartz specimens on my claim and the gold content is so low as to be not even worth the effort other than a nice rock for the mantel...
But keep looking quartz with the red iron and black sand in it means the conditions are right, just is no cigar on this one. Dump truck you may wish to find out where they picked the load of stone at and go for a look see.... that is if you can remember the who and where part.
