Newmont Mining Corporation, Phoenix Mine Geology Manager
I graduated with a B.A. in Geology from Whitman College, Walla Walla, Washington in 1986, and promptly went to work driving a truck for the Bonanza Produce Company in Reno, Nevada. In early 1989, I ran into a college Ultimate Frisbee acquaintance who was working for an exploration company in Sparks, and he sug-gested I get a resume together and get back into geology.
I took my first geology job in June of 1989 (with a $4,000/yr cut in pay!) with Nevada Goldfields at the Aurora Mine, Mineral County, doing ore control. (As a side note, Great Basin Gold just purchased the Aurora mill to process their Hollister Mine ore). It was a small project, with about 50 employees and a 250 ton/day mill producing about 1,000 oz. Au/month, but it was a great opportunity to get exposed to mining, geologic mapping, and sampling in open-pit and underground settings. As a side note, Great Basin Gold just purchased the Aurora mill to process their Hollister mine ore.
I quit Nevada Goldfields in 1991 to attend the Mackay School of Mines and pursue an M.S. under Dr. Don Noble. I did my M.S. on the structure, geochemistry, and temporal relationships between the low-sulfidation mineralization in the Aurora district and the adjacent high-sulfidation Brawley Peaks prospect. At the top of East Brawley Peak, one of the Miocene vents from which the andesitic volcanics that host the Aurora veins erupted, is a NW-striking, dilatant jog that is still undrilled today. What are coarse quartz vein fragments containing fluid inclusions with variable compositions, some with liquid CO2, some with halite daughter minerals, and some that don’t homogenize at 500°C, doing in an outcrop at 9,400’ elevation?
After my coursework was completed in 1993, I took a job doing ore control at Twin Creeks for Santa Fe Pacific Gold Corp. After the Newmont merger, I was exposed to RC-chip and core logging and three-dimensional modeling. The understanding of the sedimentary rock package that hosts Twin Creeks greatly advanced when exploration geologists working out of the Newmont office in Winnemucca completed a significant re-logging campaign and reinterpreted the stratigraphy of the Comus Formation. Passing on those geologic observations were, in part, what motivated several of us working at Twin Creeks to update the geology of the deposit in the 2005 GSN symposium proceedings.
I took an opportunity to travel to Peru and work at Yanacocha from mid-2000 to mid-2001, on a rotating six-week-on, two –week-off schedule, logging core and then mapping road-cuts and drill pads in the Yanacocha and Carachugo/Chaquicocha subdistricts. In December of 2000, we completed the first mine geology compilation map of the Yanacocha subdistrict. Walking and mapping road-cuts and exposures outside of the pits on those 12,000’ mountains was my favorite job yet in geology.
I returned to Twin Creeks in June of 2001, again doing ore control. In 2002, I had the opportunity to update the geologic map of the south end of Mega pit and then update the digital model based on my mapping. In 2003, I executed a drill program expanding on drilling Goldfields began earlier in section 30.
John Winton Erwin*
Erin L. Hart
Greg T. Hill
Joseph Kizis, Jr
Brooke J Miller
Justin and Ajeet Milliard
Mia (Cowgill) O'Neal
Shea Clark Smith
Roger C Steininger