Tin sources and trade in ancient times shapes cast in closed molds of the Bronze Age. Arsenical bronze objects appear first in the Middle East where arsenic is commonly found in association with copper ore, but the health risks were quickly realized and the quest for sources of the much less hazardous tin ores began early in the Bronze Age . This created the demand for rare tin metal and formed a trade network that linked the distant sources of tin to the markets of Bronze Age cultures. Cassiterite (SnO), oxidized tin, most likely was the original source of tin in ancient times. Other forms of tin
Antimicrobial copper-alloy touch surfaces in rooms with copper touch surfaces were significantly lower than in rooms without copper surfaces. "Staphylococci" were the most predominant microorganism isolated and copper was effective in reducing the "Staphylococci" microbial burden. Further studies regarding the clinical implications of copper's intrinsic ability to reduce microbial burdens in hospitals are being planned. Researchers from the Kitasato University School of Medicine conducted antimicrobial studies of "S. aureus", "E. coli", and "P. aeruginosa" on various Japanese copper alloy coins and on copper alloy plates. The microbes were strains from hospital environments. Copper and its nickel-silver, cupronickel, and brass alloys were found to kill