Apple Valley’s Dinah Shumway, an economic geologist, discusses challenges facing miners
All that glitters is not gold.
I knew that.
But not until speaking with Dinah Shumway did I learn that not every mineral deposit is ore.
“ By definition,” she said, “ore is not ore unless you can make a profit from it.
“ Hobbyists tell me they find gold all the time. But can they mine it for a profit?”
The principal geologist for TerraMins Inc. of Victorville, Shumway is an economic geologist specializing in industrial minerals.
“ As opposed to metals,” she said, “which are classified by their intrinsic characteristics — ductility, malleability, luster, etc. — industrial minerals are classified by their uses: for example, calcium carbonate, which is used to make Portland cement, carpet backing, linoleum, even the powder on chewing gum.
“ Calcium carbonate probably has more uses than any other mineral — although the boron industry would claim that honor for borax.”
According to the U.S. Geological Survey Mineral Information Service, Portland cement and construction aggregate (the sand, gravel and crushed rock that are mixed with cement in order to make concrete) represent 70 percent of California’s total non-fuel mineral production.
The chief ingredient in Portland cement is calcium oxide.
To transform calcium carbonate, which is found in limestone and marble, into calcium oxide, raw ore is heated to above 2,500 F. Not only is this “cooking” expensive, but so is transporting the finished product.
Likewise, Shumway said, “Although the sand and gravel used to make concrete are cheap to mine by volume, they are horrendously expensive to transport. The cost of hauling doubles with every 25 miles.”
She added that the south side of the San Gabriel Mountains contains some of the best sand and gravel in the world. But the presence of the Anheuser-Busch plant — not to mention all that expensive housing — means most of the area is off-limits to miners.
As an economic geologist, Shumway wishes people would learn what’s underground before building houses on top of potentially rich deposits:
“ The presence of a house of even the lowest quality tends to mean a site will never be mined.”
And yet, there have been times when mining companies have moved entire towns in order to get at ore.
Why go to such trouble? Because high demand for a mineral makes the expense of extracting it worthwhile.
Shumway added that “when the price of gold, for example, goes up, people may find it pays to mine a lower grade of ore. Many companies stockpile their lowest-grade material until the market price makes it worth the trouble.”
The discovery of a new use for a mineral — even a new need for a particular color of clay — can increase the value of a deposit.
When I asked if — rather than digging up Pasadena — we couldn’t simply recycle minerals, Shumway said no, not necessarily: “Forestry and farming are classic examples of sustainable industries. As new crops are sown and the soil fed with nutrients, forestry and farming become a matter of management.
“ Mines, on the other hand, represent a net loss to the crust. This is because we use minerals to make something useful, and not all minerals can be recycled.
“ You can recycle concrete, for example, but not for the highest-end uses like building dams.”
In the mining industry, therefore, sustainability means having a stream of new, available ores to take the place of depleted deposits.
Here “available” is as critical as “new.”
“ When we evaluate a property,” Shumway said, “we might find the location is great and the ore is of high quality, but we cannot get a permit to mine there.”
She added that California has the richest variety of ores in the United States, “except perhaps Alaska, but we may not even explore in Alaska’s wilderness areas.”
Raised in Lakewood and Long Beach, Shumway is married to Doug Shumway, the environmental director for Mitsubishi Cement Corp. in Lucerne Valley. According to Dinah Shumway, Lucerne Valley as one of the most important mining sites in the nation because the limestone found there is of a superior quality and can also be mined economically.
Today they live in Apple Valley. But from 1971 to 1985, the couple traveled from one mining town to another.
“ Mining is like the Army,” Dinah Shumway said. “You meet the same people over and over again.”
Shumway belongs to Women in Mining (WIM), which was founded in 1972 to educate its members — and also the general public — about the various mining industries.
Today the nonprofit organization is open to men as well as women.
Among WIM’s projects is teaching children and teenagers about the role of mining in their daily lives.
“ Unless you have minerals, you don’t have chemicals,” Shumway said. “Indeed, everything we use is either made directly from minerals, manufactured from something made from minerals or transported by something made from minerals.”
As the WIM Web site points out, minerals are used to treat everything from burns to bipolar affective disorder. Even the oohs and ahs of fireworks depend on mineral compounds: copper for blues, sodium for yellows, barium for bright greens, strontium for deep reds, etc.
Apropos of strontium, Shumway explained why, every holiday season, we are warned against burning colored wrapping-paper in fireplaces:
“ Chromium and strontium are what make the pretty colors. At the very low heat of a wood stove, these go right into the air.”
WIM also stresses the social importance of minerals.
“ The discovery of the Mother Lode was the seminal event in Western history,” Shumway declared. “No other event mobilized so many people in so short a time.
“ Most of the people who came west to mine had never been miners. They were younger sons and adventurers. And yet, in the first 16 years of California’s gold rush, more than 3 million ounces were extracted, all by the simplest methods possible.”
Then, facing head-on that bane of modern miners — native habitats — she said: “There were other native plants before the present species.”