According to the Minerals Education Coalition, most arsenic is obtained as a by-product in the treatment of gold, silver, copper and other metal ores. The majority of the world's arsenic comes from copper-gold deposits in Chile, Mexico and China.
Albertus Magnus discovered arsenic in 1250 C.E. when he heated soap together with arsenic trisulphide. The early Chinese, Greek and Egyptian civilizations also mined arsenic and discovered its toxic properties.
Today, most arsenic is obtained by heating arsenopyrite to produce the compounds used in rat poison and some insecticides. Small amounts of arsenic are also added to germanium to make transistors, and laser light electricity in the form of gallium arsenide. As a metalloid, arsenic conducts some electricity like a metal; however, not all the electricity is a true conductor like copper would conduct. Arsenic compounds are extremely poisonous; therefore, extreme caution has to be taken when extracting the compound from metal ores.
Most countries have banned arsenic from being used in insecticide sprayed in fields and orchards because of its poisonous properties. According to Minerals Education Coalition, the majority of U.S. arsenic consumption is in the form of chromated copper arsenate, a chemical used as a wood preservative for telephone poles, fence posts, pilings and foundation timbers.