"The art of tempering and casting iron developed in India long before its known appearance in Europe; , for example, erected at Delhi (ca. 380 A.D.) an iron pillar that stands untarnished today after fifteen centuries; and the quality of metal, or manner of treatment, which has preserved it from rust or decay is still a mystery to modern metallurgical science. Before the European invasion the smelting of iron in small charcoal furnaces was one of the major industries of India. The Industrial Revolution taught Europe how to carry out these processes more cheaply on a larger scale, and the Indian industry died under the competition. Only in our own time are the rich mineral resources of India being again exploited and explored."