The rise of Britain as an industrial nation in the late eighteenth and early nineteenth centuries was partly due to the presence of considerable mineral resources, which provided raw materials as well as sources of power. She possessed abundant supplies of coal and an adequacy of iron ore — the two chief minerals on which the Industrial Revolution was based. Coal has been worked in Britain for 700 years, and as an industry, coal-mining has been in existence for over 300 years, twice as long as in any other European country. For over a century coal was the most important source of power and fuel in Britain. She had enough non-ferrous metals — copper, lead, ajid tin, for example, to meet her needs for a time. But in the course of the last hundred years or so the situation has gradually changed. Many of Britain’s most valuable and accessible deposits have been worked out. Moreover, coal has lost some of its former importance, and such minerals as petroleum and uranium ores have become essential materials in the modern, world. At the same time British industry has become increasingly orientated towards lighter industry, and the heavier coal-field-based industries have tended to decline as the dependence upon coal as a source of power has declined. The absence in Great Britain of high-grade iron ore, manganese, chrome, nickel and many other rare metals makes her economy greatly dependent on imported raw materials.