Amalgam (chemistry) gold") would not be extractable from ore using hydro-mechanical methods. Large amounts of mercury were used in "placer mining", where deposits composed largely of decomposed granite slurry were separated in long runs of "riffle boxes", with mercury dumped in at the head of the run. The amalgam formed is a heavy solid mass of dull gray color. (The use of mercury in 19th century placer mining in California, now prohibited, has caused extensive pollution problems in riverine and estuarine environments, ongoing to this day.) Sometimes substantial slugs of amalgam are found in downstream river and creek bottoms by amateur wet-suited
Dental amalgam controversy years. All available world-wide research indicates that amalgam is not harmful to health... No Government or reputable scientific, medical or dental body anywhere in the world accepts, on any published evidence, that dental amalgam is a hazard to health." The Irish Dental Association provides additional detail in a published patient information letter. France has publicly recognized the safety and effectiveness of amalgam restorations. A position paper on the Association Dentaire Française website states that amalgam restorations have proven to have no biological or toxic effect. They also mention that no serious pathological fact has ever been observed and no general