Since the discovery of precious opal at Stuart's Range, now called Coober Pedy, in 1916, South Australia has become the major world producer of precious opal. Although the industry's growth has been hampered by two world wars and harsh climatic conditions, and opal is only a luxury, non-essential item, the industry has had a marked revival since 1959. The estimated value of annual production was a record in 1978, being approximately 25% of the total value of all minerals produced in South Australia in that year. A method of estimating the value of opal production has been devised, based on the number of opal miners, cost of living, capital cost of equipment, and operating expenses. By this method, opal worth $42 million was produced in South Australia during 1978.