I know some that are fanatics and will even trespass on a rained on plowed field, if they know a vein runs through the area. we used to find them pretty regularly around a camp I was in, but there was a mound on the property so it made sense we were near a vein. never found any on the mound...mostly in runoff ditches and ag fields along those ditches.
true arrowhead/ artifact hunters use a probe (most are old metal antennas from cars, sharpened to a point).