The geology at Koegas is distinctive. Asbestos fibers run vertically through bands of ironstone rock, and intense geological folding along normal and reverse faults has stacked multiple bands atop one another in the Westerberg deposit, creating an unusually concentrated ore body. Nine reefs are present, with the overall deposit measuring 150 feet thick. The fibers are blue because of their iron protoxide content, and they are notably stronger than the white chrysotile asbestos found elsewhere. This combination of quality and concentration made Koegas valuable. It also made it deadly. Crocidolite, or blue asbestos, is the most hazardous form of the mineral, its fine needle-like fibers penetrating deep into lung tissue where the body cannot break them down.

Cape Asbestos Company Limited opened the mine in 1893, but early operations were small-scale and unprofitable. The mine produced nothing at all in 1903. When production resumed in 1907, it turned a modest profit of 6,900 pounds. The First World War transformed the operation: demand for asbestos insulation soared, and Koegas expanded rapidly. The Great Depression brought another downturn, but the Second World War and the post-war economic boom pushed production to new heights. At its peak, up to 5,000 miners worked the site, drawing labor from Prieska, Griquatown, and as far away as Botswana, Zimbabwe, and Malawi. By 1977, South Africa was the world's third-largest asbestos supplier, extracting 380,000 long tons that year.

The underground workforce was male, but women and children were employed above ground to break asbestos into fibers by hand and sort them into grades. Mine inspectors raised safety concerns throughout the operation's history. Housing, sanitation, and medical facilities were consistently judged substandard. When inspectors demanded improvements, mine directors refused, claiming the deposits would be exhausted within a decade -- an excuse they repeated for decades. In 1962, the South African Pneumoconiosis Research Unit published a report documenting high levels of mesothelioma in Prieska, but the asbestos industry suppressed the findings. Scurvy and tuberculosis epidemics swept the mine. Workers who fell ill with asbestosis often remained on site, and many died there. The company's response was to move their widows to Marydale.

In 1998, former workers and their families filed suit against Cape Plc in the English High Court. Cape argued that because the mine had been owned by its South African subsidiary, the case belonged in South African courts. The matter climbed to the House of Lords, then Britain's highest court of appeal. In the landmark ruling Lubbe v Cape plc, the law lords held that a British parent company owed a duty of care to employees of its overseas subsidiaries and allowed the case to proceed in England. Cape eventually settled out of court, paying 21 million pounds to claimants who had suffered illness from the mine's operations. The ruling established a precedent that resonated far beyond asbestos law, affirming that multinational corporations could not shield themselves from liability by routing operations through foreign subsidiaries.

The South African government began cleaning up the Koegas site in 2007. Tailings have been sown with grass and fenced off. The most accessible asbestos has been removed. But the mine's legacy is woven into Prieska itself. Streets in the town were paved with asphalt containing asbestos. Buildings were constructed with asbestos cement walls and roofs. In 1985, Prieska was declared a dust control town, requiring the waste piles to be covered with soil -- an acknowledgment that the mineral that had driven the local economy for nearly a century was poisoning the community that depended on it. From the air, the site is unremarkable: fenced ground, reseeded earth, the faint geometry of roads that once carried trucks loaded with blue fiber. The ordinariness is the point. The damage was never visible from a distance.