Great hike - thanks to Joe for writing it up. Would not have known about it otherwise. For our hike the wild flowers were blooming, temps were in the 60s, and not a soul on the trail to interrupt the solitude (except for my hiking partners) or break the vistas. Isn't it great to live in Arizona. Look up cinnabar on wikipedia to get some additional info and history about it before going. Also from wikipedia:

"Abandoned mercury mine processing sites often contain very hazardous waste piles of roasted cinnabar calcines. Water runoff from such sites is a recognized source of ecological damage

Historically, mercury was used extensively in hydraulic gold mining in order to help the gold to sink through the flowing water-gravel mixture. Thin mercury particles may form mercury-gold amalgam and therefore increase the gold recovery rates.[3] Large scale use of mercury stopped in the 1960s. However, mercury is still used in small scale, often clandestine, gold prospection. It is estimated that 45,000 metric tons of mercury used in California for placer mining have not been recovered.[56] Mercury was also used in silver mining."

Caution: I would not drink the water from Sycamore Creek or its tributaries. Also, if you pick up some cinnabar when visiting the mines/plant and take it home to process, be aware that many people have died at home from inhalation of mercury fumes when they tried to refine gold from old jewelry (or drive off the mercury from cinnabar).