In Cottonwood, a towering 50-foot pile of black slag—leftover waste from a copper smelter shut down in the 1930s—has become a fixture near homes, the Verde Valley Fairgrounds, a playground, low-income apartments, and the local VFW post.
For decades the slag sat mostly untouched, but since 2015, Minerals Research Inc. has been crushing it into material for industrial uses like paving and roofing. Residents say the process creates persistent black dust that settles on cars, in yards, and inside homes and businesses—even with windows closed.
Neighbors worry the slag contains heavy metals like arsenic, which can lead to respiratory issues, lung disease, or cancer with prolonged exposure.
The Arizona Department of Environmental Quality has investigated after complaints about visible dust blowing off-site. Testing in recent years found elevated arsenic in nearby soil samples—some far above state remediation levels—though ADEQ says sources could include historic smelting, the current operations, or natural deposits. More comprehensive soil and air results from late 2025 testing are expected to be shared with the community soon.
Minerals Research maintains its facility is safe, with dust controls in place, and has faced permitting issues with ADEQ, including violations and temporary shutdowns over emissions. The company calls the work “upcycling” the waste and says without it, the pile would remain in the middle of town.
The situation highlights ongoing challenges in former mining areas, where legacy contamination and modern repurposing efforts raise questions about health and environmental safety in the Verde Valley.