The history of Zika virus. The rise in the spread of Zika virus has been accompanied by a rise in cases of microcephaly and Guillain-BarrÃ© syndrome. First identified in Uganda in 1947 in monkeys, Zika was later identified in humans in 1952. The first large outbreak of disease caused by Zika infection was reported from the Island of Yap in 2007. There are currently several countries experiencing Zika virus outbreaks.
In 2014, copper mining produced about 15 metric tons of gold, worth $600 million, which represented 7% of US gold production. Other byproducts of the copper extraction process included silver, and minor amounts of rhenium and platinum-group metals.Sulfuric acid is recovered at copper smelters.opper mining activity increased in the early 2000s because of increased price: the price increased from an average of $0.76 per pound for the year 2002, to $3.02 per pound for 2007.
For example, knowing that standard 18-carat yellow gold consists of 75% gold, 12.5% silver and the remaining 12.5% of copper (all by mass), the volume of pure gold in this alloy will be 60% since gold is much denser than the other metals used: 19.32 g/cm 3 for gold, 10.49 g/cm 3 for silver and 8.96 g/cm 3 for copper.arat purity is measured as 24 times the pure mass divided by the total mass: where. Therefore, 24-karat gold is pure (also includes down to 99.95% gold by mass), 18-karat gold is 18 parts gold, 6 parts another metal (forming an alloy with 75% gold), 12-karat gold is 12 parts gold (12 parts another metal), and so forth.