COPPER MINE TAILINGS AT MILE MARKER 139 ON STATE ROAD 77, WINKELMAN, ARIZONA

SAMPLE COLLECTION SITE - Gary Foster Photograph

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SLAB FROM COLLECTION SITE (BOTH SIDES ARE SHOWN)

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I drove back to Globe yesterday. Actually, I turned off the highway at Superior and went straight to Winkelman on Highway 177 to see that mound of dark material again and do some amateur research. I should have been more astute. The sign reads Copper Corridor; so that should have been a giveaway as to what I encountered the other day when I passed through here on my one-day trip.

I looked at the black mound again, this time more closely, and came to the conclusion that it’s a small volcanic vent that popped up a million years ago. Still, there was lingering doubt. I wanted to inquire at the mine but it’s not working as the miners are on strike.

I drove back to Winkelman and explored the town. Pretty small. There was a street that went to the top of the hill where a high school sits and I had a grand view of the mound. It’s bigger than I thought. I thought I would inquire in the town as to its origins. I encountered a maintenance worker driving his vehicle out of the school and I could not have been more lucky. His name was Hector Moreno and he was (is) of all things a mining engineer who got laid off a few years ago. Of Mexican heritage and perfectly bilingual, he was born and raised around Globe and comes from a mining family. I asked him point blank if the black mound is an old volcano. He laughed and said no. “It’s called the Slag Dump.” It’s the remnants of the copper ore that is processed at the plant. The resulting black slag is hauled away in a giant kettle by trucks and poured down the side of the heap or, I suppose, on top, too. Interestingly, he said it’s so hot that it glows and lights up the entire valley at night, all night long. So, my theory of the mound being a volcano is incorrect and the black material, as your colleagues rightly pointed out, is not of volcanic origin but the results of the copper ore process. I was disappointed and also elated. How interesting to learn that? Hector was knowledgeable and very articulate about the mining industry in the area. I could not have stopped a better person to obtain such information. And there you have it. - Gary Foster

COLLECTION SITE OF ROCK SLAB

COLLECTION SITE LANDSCAPE

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SLAG PILE

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GRAIN DISTRIBUTION CHARACTERISTICS (AGI CHART)

GRAIN SHAPE CHARACTERISTICS

(PREPARED BY GAMMA ZETA CHAPTER , SIGMA GAMMA EPSILON, KENT STATE UNIVERSITY - AGI CHART))

Roundness is the degree of smoothing due to abrasion of sedimentary particles. It is expressed as the ratio of the average radius of curvature of the edges or corners to the radius of curvature of the maximum inscribed sphere.

The sphericity of a particle is: the ratio of the surface area of a sphere (with the same volume as the given particle) to the surface area of the particle.

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