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Asbestos can be any of several minerals which readily separate into long, flexible fibers. The most known type of asbestos is chrysotile, the fibrous form of the mineral serpentine, which accounts for about 95% of all asbestos in commercial use. The other types include the fibrous forms of anthophyllite, amosite, cro- cidolite, tremolite, and actinolite. Asbestos has been mined for over 4000 years with the earliest evidence dating to around 2500 BC. Despite being valued since an- cient times for its fire-resistant properties, asbestos fiber did not achieve commercial relevance until the 19th century. Modern as- bestos production began at a mine in Italy in 1868, and large-scale production from deposits in Quebec began in 1878. Production waned in the late 20th century due to the health hazards posed by the mineral. After mining, the asbestos fiber is freed by crushing the rock, then it is separated from the surrounding material, usually by a blowing process. Roofing products containing asbestos account for more than half of U.S. consumption. Friction products such as brake pads and gaskets account for about another 20%. Asbestos is also used for some specialized concrete products. Arsenic occurs in pure form exclusively in small deposits. It occurs in many minerals, and usually is obtained as a by-product from the mining, processing, and refining of other minerals. From the time of the Roman Empire through the Victorian era, arsenic was considered the "king of poisons" and the "poison of kings." But even with its reputation as a poisonous substance, ar- senic still holds an important place in the natural world and is a valued mineral. Common arsenic- bearing minerals include arsenopyrite, conichalcite, enargite, lollingite, olivenite, and orpiment. Most collectible arsenic comes from various mines in Europe, and the mineral is also mined in China, Chile, Russia, Mexico, and the Philippines. Arsenic is sometimes alloyed with lead to form a harder, more durable metal. It is used in py- rotechnics to give additional color to the flame. Some additional areas of use include car batteries and bullets. Arsenic is critical to the health of some species, including humans, which contain within the body an arsenic percentage of 0.00001%. It is necessary for the functioning of the nervous system, and a deficiency can lead to inhibited growth. The World of Minerals --- *+ )#)('-()$* !(& )(%#'" +)""+ ,'.*,+ -'"/ 0 . 1 1 1 1 29 WorldWide Drilling Resource ® JULY 2017