The state moved from fourth to third in proved reserves in 1975. In the 1980s uranium ranked second in value among the metallic minerals mined in Texas, and Texas ranked fifth among the states in output. A number of uranium deposits were discovered within a belt of strata extending 250 miles from the middle Coastal Plain southwestward to the Rio Grande, but decreased demand and price of uranium after 1980 brought a sharp decline in Texas operations. In 1984 uranium reserves and resources were estimated at 310,000 short tons, or 620 million pounds, of which 50,000 tons were judged as measured reserves, 75,000 tons were inferred reserves, and 185,000 tons were undiscovered. Production of uranium concentrate was about 5.4 million pounds annually. Uranium Resources Incorporated, Dallas, which marketed its uranium production to electric utilities, began production at its Rosita Mine, planned to become one of the world's lowest cost uranium mines, late in 1990.