Arizona Geological Society Presents: Chris Osterman, PhD 417 Project, Globe, Gila County, Arizona A Native Silver Discovery

Abridged Abstract. The 417 Project lies 10 km due north of the copper min­ing town of Globe, Arizona, and 112 km east of Phoenix, Arizona. The “417” consists of 100 unpatented lode claims covering an area where an extraordinary amount of alluvial native silver was found by metal detectorists over the last two years. Twenty five, large (over 0.5 kg), silver nuggets totalling over 10,700 ounces (330 kg) were spread over a 560 meters length of a dry arroyo locally known as Mexican Mine Canyon. The silver nuggets range in weight from 30 grams to up to 190 kilograms (417 lbs) and notably decrease in size down the gradient of the arroyo. The largest nuggets, 36 kg, 55 kg, and 190 kg occur 25 meters downslope of a 300 m long, east-west striking, 40 cm wide, quartz-sider­ite brecciated vein. Although one historic 4 m deep prospect pit occurs on the vein, there are no indications of native silver in the pit walls or in dump materi­al. The obvious source of the silver lies in the east-west vein.

Silver nuggets from the Globe, Arizona area on display at UArizona Alfie Norville Gem & Mineral Museum, Tucson. Largest nugget weighs 190 kg.