ID Help Please

[billdean]

I friend of mine found this rock. He seems to think it has some value. On his monster 1000, and Equinox 800 it reads as having some gold in it, or it at least has some non-ferious properties to it. It just looks like lava rock to me. It is very light for it size, less than a few ounces. It was found a little west of Phoenix, Arizona. Any ideas?

[jasong]

Scoria or pumice. Or maybe slag.

Drop it in water, if it floats it's a witch. Err, it's pumice. If it sinks it's scoria (they are basically the same, just more/less dense). Or it's slag but usually slag is a bit heavier than both of them. 

andesite->basalt tends to be hot on detectors. Pumices/scorias are actually pretty much just in that series, they just have lots more vesicles making them lighter. There is a lot of old cinder around Central AZ which along with the density makes me think that instead of slag.

[billdean]

Thanks jasong! I wonder why it sounds non-furious, Gold/aluminum on a metal detector?

[jasong]

3 hours ago, billdean said:

Thanks jasong! I wonder why it sounds non-furious, Gold/aluminum on a metal detector?

Can't help ya with that one, I have basically no experience running a TID detector anywhere except yards and parks. Only detectors I use where I encounter stuff like that are all non discrim machines, but that kind of rock can definitely sound like a good target sometimes on them.