form of the amphibole riebeckite, found primarily in southern Africa, but also in Australia and Bolivia. One formula given for crocidolite is . Crocidolite is seen under a microscope as a blue fiber. Crocidolite commonly occurs as soft friable fibers. Asbestiform amphibole may also occur as soft friable fibers but some varieties such as amosite are commonly straighter. All forms of asbestos are fibrillar in that they are composed of fibers with breadths less than 1 micrometer in bundles of very great widths. Asbestos with particularly fine fibers is also referred to as "amianthus". Other materials Other regulated asbestos minerals, such as tremolite asbestos, CAS No. , ; actinolite asbestos, CAS No. 77536-66-4, ; and anthophyllite asbestos, CAS No. , ; are less commonly used industrially but can still be found in a variety of construction materials and insulation materials and have been used in a few consumer products. Other natural asbestiform minerals, such as richterite, , and winchite, , though not regulated, are said by some to be no less harmful than tremolite, amosite, or crocidolite. They are termed "asbestiform" rather than asbestos. Although the U.S. Occupational Safety and Health Administration (OSHA) has not included them in the asbestos standard, NIOSH and the American Thoracic Society have recommended them for inclusion as regulated materials because they may also be hazardous to health. "Mountain leather" is an old-fashioned term for flexible, sheet-like natural formations of asbestiform minerals which resemble leather. Asbestos-containing minerals known to form mountain leather include: actinolite, sepiolite, and tremolite. Production In 2017, 1.3 million tonnes of asbestos were mined worldwide. Russia was the largest producer with 53% of the world total, followed by Kazakhstan (16%), China (15%), and Brazil (11.5%). Asia consumes some 70% of the asbestos produced in the world with China, India and Indonesia the largest consumers. In 2009, about 9% of the world's asbestos production was mined in Canada. In late 2011, Canada's remaining two asbestos mines, both located in Quebec, halted operations. In September 2012, the Quebec government halted asbestos mining. Health impact The most common diseases associated with chronic asbestos exposure are asbestosis (scarring of the lungs due to asbestos inhalation) and mesothelioma (cancer associated with asbestos). Mesothelioma is an aggressive form of cancer and often leads to a life expectancy of less than 12 months after diagnosis. All types of asbestos fibers are known to cause serious health hazards in humans