Something other than water descends from Tuolumne County to sustain farming in the San Joaquin Valley.
Limestone, quarried and crushed near Columbia, is spread on cropland and enriches the diets of poultry and cattle. It goes as well to glass plants, some of them making bottles for California wine.
The stuff comes from Blue Mountain Minerals, which has operated since 1988 at a site that, starting in the 1850s, yielded marble slabs with the same chemical makeup.
The 46-employee company is the largest limestone producer in Northern California. The pit reaches down several hundred feet on a hillside overlooking New Melones Reservoir.
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“Limestone is found everywhere, but large quantities of high-quality limestone are found in few places,” said Jeff Redoutey, chief executive officer at Blue Mountain, during a tour last week.
He declined to say how much limestone the quarry produces, other than that it exceeds 500,000 tons a year. The privately held company also does not disclose annual sales.
Farms and glass plants are the biggest users, but limestone also ends up in concrete, road base, stucco and other construction materials. It’s in adhesives and diapers and poker chips and more.
“Just look around this room,” said Jay Esty, director of sales and marketing, at the conference table where the tour started. He noted that there’s limestone in ceiling tiles, floor tiles, windows and paint.
The tour continued on to the blasting and crushing steps that turn big chunks of the grayish white rock into much smaller pieces. Some of them are as fine as baby powder, sitting in stockpiles that create a moonscape feel amid the foothill trees and brush.
Gold Rush roots
The quarry started soon after gold miners arrived in Columbia in 1850. It produced marble under several owners for decades after the Gold Rush faded.
A 1909 promotional book, “Tuolumne County, California,” described how the quarry “turns out a product that in beauty, durability and susceptibility to a brilliant polish is the peer of any in the world.”
The book tells how workers used machinery of the day to cut marble blocks of about 380 tons from the deposit. They split these into 15-ton blocks, then sawed them into sizes desired by the buyers.
The slabs became floors and walls in banks, mantels and counters in homes, tombstones in cemeteries, even dividers in public restroom stalls. They adorn the Tuolumne County Courthouse and the Sonora Veterans Memorial across the street. Much of the product went into structures built amid the rubble of the 1906 earthquake and fire in San Francisco.
Production continued through the 1920s, but the Depression put an end to the marble business. Various operators produced crushed rock over the next several decades, including one that until the 1990s supplied a Sonora producer of lime, used for construction and other purposes.
The story is told in a new book, “Marble: Historic Columbia’s Gray Gold,” by Carlo De Ferrari, the county’s official historian.
The pit now worked by Blue Mountain is about 500 feet deep, and its county permit allows an additional 200 feet. Redoutey said that means about 40 more years of operation, but the deposit is likely deep enough to produce for many years beyond that.
The process starts with blasting about every 10 days along benches 40 to 80 feet high. This leaves rocks up to 4 feet in diameter, which are fed into a crusher that takes them to 4 inches or less. After washing to remove clay, a second crusher reduces the rock to 1 1/2 inches or less. The final crushing leaves the rock in whatever size the buyer ordered – from larger road and drain rock to the powder spread on cropland.
Limestone’s scientific name is calcium carbonate, made up of calcium and carbon molecules. Blue Mountain also produces dolomite, a form that also contains magnesium and goes to farm, glass and other uses. And it sells a very small number of the marble slabs that were big business long ago.
The company owns 1,226 acres, but most of it is an undisturbed buffer around the 336 acres being quarried.
“This is a great place to mine,” Redoutey said. “It’s all by itself. People wouldn’t know it’s here except for the trucks leaving.”
The permit has measures for controlling dust, water pollution, noise and other impacts. A recent expansion raised concerns from the Central Sierra Environmental Resource Center, leading to more detailed study of the effects. Blue Mountain also has a reclamation plan that includes replanting much of the disturbed ground.
Blue Mountain has sold limestone for use in emission controls on coal-fired power plants, but that business has shrunk as California has moved away from this energy source.
The company supplies eight glass plants in the state, but it declined to say whether they include the massive Gallo Glass Co. in Modesto, which serves the adjacent winery.
The largest use is Central Valley agriculture, including 35 feed mills and more than 100 farm supply stores. The mills add a little limestone to the mostly grain diets of cattle and poultry, enhancing their bone health. The calcium helps hens lay eggs with sturdy shells.
Farmers use limestone to reduce the acidity of soil and improve the uptake of other nutrients.
Martin Bianchi, fertilizer coordinator at Stanislaus Farm Supply near Ceres, said Blue Mountain provides a high-quality product for row crops, trees and other uses.
“We go through probably 15,000 to 18,000 tons from them a year,” he said, adding that Columbia is a shorter trucking distance than many other suppliers.
Limestone is allowed under federal standards for organic agriculture.
“It’s just crushed rock,” said Christina Johnson, agricultural sales manager at Blue Mountain. “It comes out of the ground and goes back into the ground.”
John Holland: 209-578-2385
The rock, one of the most common on Earth, formed mainly from skeletons of marine organisms in ancient and present-day seabeds. “Molluscs use it for their shells, corals for their reefs, birds for their eggs, etc.,” said a 1909 book on Tuolumne County. “It is found in the bones of animals, in certain forms of plant life – in a myriad of animate and inanimate objects.”
▪ Details on Blue Mountain Minerals’ products and history are at www.bluemountainminerals.com.
▪ Carlo DeFerrari’s history of the local industry, “Marble: Columbia’s Gray Gold,” can be purchased from the Tuolumne County Historical Society at www.tchistory.org. The cost is $25 plus $6 for shipping.