The periodic table lists 17 rare-earth minerals. Clockwise from top left is allanite, containing cerium; agardite containing yttrium; lanthanite containing neodymium used in alloys for permanent magnets and glass; and davidite, known to be found in Pima County, which has lanthanum, used in o…
Mining companies are trying to manage the problems with tailings, such as these at the Asarco mine near Green Valley. Among the procedures Asarco is using to control dust is spraying additives onto tailings to create a crust that's less likely to blow off.
An Asarco mining operation has agreed to pay a $60,000 fine and take preventive steps valued at $50,000 to resolve water-quality violations caused by a June 2010 pipeline spill at the Silver Bell Copper Mine near Marana, state regulators said Tuesday.
The dollar value of hard-rock minerals mined on federal land by companies is unknown because royalties from the sale of those minerals aren't paid to the federal government, a new report said Wednesday.