Was out using my new Kellyco purchased Nokta AU Gold Detector in southern Arizona a couple of weeks ago looking for the allusive yellow stone and got a hit on this. Had it confirmed last Tuesday as a Civil War era .58 caliber musket ball slug. I am assuming it would have been spent during the gold times of the mid to late 1800's due to location and depth. The confirmation I got was from a well versed early military historian metal detectorist. Only problem is I've not hit my first yellow nugget yet.