By Damien Knight
Every time one watches T.V. one cannot avoid hearing the commercials for “asbestos” and its dangers. “Have you been diagnosed with Mesothelioma?” the ad asks. This paper discuss what asbestos is and its applications in commercial industries. We will first define “asbestos”, describe the minerals defined, talk about its use in our economy and speak in depth about the serpentine mineral chrysolite.
The confusion over asbestos health risks is due to the term does not refer to a single mineral. Asbestos is an industry term that covers six different naturally occurring minerals. These minerals or “asbestiforms” all have a fibrous habit that is strong and flexible. The fibers are soft like fabric and can be spun into yarn or made into felts. This makes them useful as a fireproofing and insulation material.
The asbestos minerals are serpentine and amphibole minerals. 95% of asbestos used in buildings is chrysotile the serpentine asbestiform. Chrysotile’s chemical formula is Mg3Si2O5(OH) 4. It is both greasy and silky, with a fibrous habit and a hardness between 3 and 5. Chrysotile is mined in Russia and Canada. The mining is done using dry-milling. Ore is crushed then dried and crushed again to be extracted.
The other asbestos minerals are the amphiboles. These minerals exhibit solid solution and are more needle-like than chrysotile. They are riebeckite in the form of crocidolite, grunerite in the form of amosite, anthophyllite, tremolite, and actinolite. These five amphibole minerals are harder than the chrysotile. They have smooth less flexible fibers that are thicker and more needle-like. It is these asbestiform minerals that are more dangerous due to being less soluble in lung fluids. 5% of all asbestos used in the united states is amphibole asbestos.
Crocidolite made around 4% of the worlds asbestos production. Crocidolite also known as blue asbestos, is the asbestiform variation of riebeckite. Its chemical formula is Na2Fe32+Fe23+Si8O22(OH) 2. Production in South Africa ceased in 1995. Australia has reserves which have not been mined since 1966. Crocidolite is found with Precambrian banded-iron formations. Oxidised crocidolite is found in quartz is used in jewellery as tiger’s eye. Crocidolite is a much higher industrial health risk than Chrysotile, and the most cancerous form of asbestos.
Commercially asbestos is used as fire retardation and insulation material. Its main commercial properties are insulation, reinforcement, inflammability, absorption, and friction. Asbestos is divided into classes of product based on the above properties. Due to health concerns some products are no longer used like asbestos roofing or loose asbestos sprays. The main asbestos products today are asbestos rubber and cements.
Most asbestos in use today is chrysotile. This mineral is monoclinic with soft fibers and some solid solution. It is soluble in the lungs only remaining in lung fluid for up to nine months. The fibers are hallowed straw like fibers. Chrysotile can be orthorhombic or monoclinic with a hardness of 3 to 5 and a specific gravity between 2.5 and 2.6.
The issue with the term asbestos and asbestiform is that it is not just one mineral. For this reason, current regulations in the industry does not regulate against individual minerals and its harmfulness. Mining asbestos is where it is most hazardous, and the news does not make this distinction hyping fear. Low levels of environmental exposure have proven relatively safe.
Klein, C., Dutrow, B., & Dana, J. D. (2008). The 23rd edition of the manual of mineral science: (after James D. Dana). Hoboken, NJ: J. Wiley.
Virta, R. L. (n.d.). Asbestos: Geology, Mineralogy, Mining, and Uses . U.S. DEPARTMENT OF THE INTERIOR U.S. GEOLOGICAL SURVEY , 4-28. Retrieved December 02, 2017, from https://pubs.usgs.gov/of/2002/of02-149/of02-149.pdf.