Asbestos:an important minerals

Asbestos is a fibrous mineral made up of long chains of silicon and oxygen. The threads of asbestos are fireproof and stronger than steel. Classified into six distinct types, asbestos is one of the most versatile rocks known to humans. Asbestos was mentioned by Theophrastus, one of Aristotle's students in his text on stones written around 300 BC. Pliny the Elder's manuscript' Natural History' written in the first century referred to 'asbestinon'. Its fire and heat resistant properties made the mineral a fantastic substance. The wonder quality of this heat and fire resistant mineral was made good use of by Europeans in the period from 1670 onwards. Its uses varied from fire-proof jackets to purses, the most famous of them being the one carried by Benjamin Franklin, American scientist. The industrial revolution and the coming of steam engines made asbestos even more popular. Some components in the engine like steam gaskets and packings were made stronger by mixing rubber with asbestos, which withstand the heat generated by the engines. Soon asbestos were being used in the construction industry for roofing and insulation. The asbestos industry saw massive growth during World War-2. The ship building and ship repai industries were the major users of asbestos during the period. The post-war construction activity saw an increase in the demand for the durable and fireproof asbestos. The link between asbestos and disease was established early in the 20th century. Asbestos fibres are capable of penetrating body tissues. The lungs in particular are very vulnerable, leading to the growth of tumours. This fibrotic lung disease was called asbestosis by W.E Cooke in 1927. The danger of asbestosis and mesothelioma - a type of tumour found in the chest or gut - cost many companies in the USA, manufacturing or dealing with asbestos, large sums of money by way of lawsuits filled by workers suffered by these diseases. India's annual production of asbestos is 25000 metric tonnes, which does not meet the demand of 1.25 lakh metric tonnes. The shortfall is made up by imports from Russia and Canada. Nearly 70 percent of the asbestos is used for making asbestos cement, corrugated sheets and pressure pipes, making the construction industry a major user in India as well. There are legislations in India regarding worker's safety and limits of asbestos dust in the air.