Image source: Library of Congress
By Rose Schreiber
They used to get this stuff from one of the hottest places on Earth—Death Valley. They used to drag it out, something like 35 tons, wagon wheels 7 feet across, tires of iron to withstand the grit, the gravel for the 160 miles to the nearest railroad. Imagine: a scorching, oppressive sun. Imagine: a long line of mules heaving an enormous load up a hill of sand, then inching down the other side, the monumental weight of it all threatening to cascade, break loose at their backs. This was Southeastern California, the 1880s. The rail terminus to which they headed, indeed, the entire settlement around it—Mojave, California—had existed for less than a decade. And yet, in no time at all, this prized material, so rare on Earth, was streaming out across the country—riding the arterial network of the transcontinental railroad, feeding a growing industrial metabolism.
Death Valley borax mining ended soon after it started, lasting only from 1883 to 1889. It first migrated south to slightly more hospitable terrain in Calico, California—a mining town whose blanched remains are now a tourist site and historical landmark. These days, as much as a third of the global supply of borax comes from an open pit some 50 miles down the road from Calico, abutting the town of Boron, California. Operated by Rio Tinto Group—a massive, multinational mining corporation—it is, today, the largest borax mine in the world, as well as the largest open-pit mine in California. Seen from above, the dry, pinkish crust of the desert has been cleaved into terraces, dusty and white. A column of rectangular pools, of rich, gradient colors, frame the western edge of the lot—between them and the terraces: fields of pale, chalky powder.
It is no surprise that borax, a soluble, boron-containing mineral, is mined here, in the desert. Boron is the real element we are after, and it is extremely rare on Earth—making up, by weight, only .001% of Earth’s crust. Boron’s scarcity, along with its mineral solubility, means that it can only be mined in places where it has accumulated as an evaporite deposit—places that are, in other words, extremely arid. Borate minerals such as borax, Ulexite, Colemanite, and the now exhausted Gerstley Borate: all of them have been sourced, primarily, from the deserts of California and Turkey, with additional deposits in Chile and Argentina. If we journey further back in time, some one thousand years, borax was once mined from dry lake beds in Tibet. Indeed, next to cobalt, it was one of the most valuable materials transported along the Silk Road.
What is it then that makes boron so valuable? Why has it been a part of global trade routes for the past one thousand years? Once used to smelt gold and silver, a vast percentage of today’s boron is used in borosilicate glass, a uniquely heat, chemical, shock, and scratch resistant material. It is found in everything from cell phones to solar panels to kitchenware. Anticorrosive and antimicrobial, borates are key to any number of manufacturing processes. It is also used in medicine, in fertilizer, in cleaners and detergents, as herbicide, fungicide, insecticide, and as a component in lithium-ion batteries.
In ceramics, we commonly think of boron as a flux, but it most certainly is not boron is a glass-former, just like silicon and aluminum. Yet, because boron melts at a significantly lower temperature than these other glass-forming elements, it has become a truly crucial component to low- and mid-temperature glazes. No other readily available material, besides lead, can melt glazes at cones 04-06. Our frits, which we have come to rely upon at low-temperature, are excellent sources of boron—not least because they are insoluble, and therefore create more consistent glaze chemistry. All of this science is by and large a 20th century phenomenon. The massive role of boron in contemporary studio ceramics is, perhaps, a powerful historical marker: of a period in which we have unprecedented understanding of, and access to, a scarce resource.
U.S. Borax currently mines borates from its open-pit mine in the aptly-named town of Boron in southern California. This region is the traditional homeland of the Yuhaaviatam Clan of the Maara’yam (Serrano) peoples, who are known today as the San Manuel Band of Mission Indians. U.S. Borax’s mine is one of the largest open-pit mines in America, and by itself it produces one third of the entire world’s refined borate products. More than 80 other minerals are found at this geologically unique site, also known as the Kramer Borax Deposit.
Southern California’s geologic history is extremely complex, so the processes that led to the Kramer deposit are difficult to pinpoint, but most of the credit goes to boron’s affinity for liquids (it is never found naturally in its elemental state) and the area’s prolific tectonic activity. The Kramer deposit was a lake of its own about 20 million years ago, and it was likely enriched with borates from subterranean thermal springs.
