With the exception of small shipments during the 1950s from the High Plains, uranium production in Texas has come primarily from the Coastal Plain. Some uranium also occurs in Trans-Pecos Texas. Surface mining, uranium-ore processing at mills, and uranium leaching from underground deposits brought to the surface through wells and stripped from the solution at in situ recovery operations have all been conducted in Texas. Rare-earth minerals, including several uranium minerals, were mined for many years from a pegmatite dike on Baringer Hill in Llano County. This locality, now beneath the waters of Lake Buchanan, was made famous by William E. Hidden of Tiffany fame, who wrote of the rare minerals there and conducted the mining operations for a time. In the intensive exploration for uranium following World War II a broad search was made in the Trans-Pecos region and in the red-bed region east of the High Plains, as well as in the Central Mineral region (the Llano Uplift). Several prospects in these regions were reported by geologists of the United States Geological Survey, the Atomic Energy Commission, and the Bureau of Economic Geology at the University of Texas. In the fall of 1954 G. H. Strodtman, a pilot for Jaffe-Martin and Associates, oil operators of San Antonio, discovered high radioactivity near old Deweesville in western Karnes County while making airborne radiometric surveys in exploring for oil. Some leases in the radioactive areas were acquired by the operators. About the same time or shortly thereafter, Clarence Ewers, while searching for opaliaed wood and testing for radioactivity with a hand counter near Tordilla Hill-a prominent cuesta in the western tip of Karnes County-discovered high radioactivity at the northern foot of the hill and found yellow uranium minerals both in sandstone rock exposures and in the soil in shallow pits that he dug nearby. "Sulfur," probably a misidentification of yellow uranium minerals, had been reported in the 1920s as occurring in this area.
Since the Texas Coastal Plain had previously been considered unlikely country for uranium, the discovery of ore of commercially interesting grade and quantity was a great surprise to many, and the discovery was followed by a mad scramble for leases and feverish prospecting by all known methods. By the summer of 1956 about fifteen prospects had been located along a narrow strip 300 miles long, extending from the vicinity of the Colorado River in Fayette County into Starr County to a few miles north of the Rio Grande. One eight-ton load of high-grade, hand-picked ore was taken from shallow pits at the foot of Tordilla Hill to a mill at Grants, New Mexico, in December 1958. The first large-scale mining was begun in July 1959 just west of old Deweesville, on Lyssy, Gembler, and Korzekwa properties. By December 1960 the San Antonio Mining Company, a locally operating subsidiary of Climax Molybdenum Company, had mined and stockpiled 100,000 tons of moderately low-grade ore-pending the building of a processing mill. In 1961 a processing mill, built and operated by Susquehanna-Western, Incorporated, using an acid-leach, solvent-extraction process, started production of "yellow cake" that assays about 78 percent uranium oxide. In the spring of 1966, after original contracts with the Atomic Energy Commission had been fulfilled, the mill was shut down for a few months, but in June 1966 it resumed operation under a new contract with the Atomic Energy Commission to furnish uranium concentrate to the West German government. All mining from 1961 to June 1967 had been done by Susquehanna-Western, but by the fall of 1966 other companies were actively securing leases in the region, as construction of nuclear reactors for the generation of electric power after 1965 fostered increased demand and exploration. Open-pit mines, located mainly along a line extending from one mile east to four miles northeast of Tordilla Hill, were as large as 120 feet deep and 500 feet wide. Ore was also produced from a mine fourteen miles northeast of Tordilla Hill (three miles east of Falls City) and from another, twenty-four miles southwest of Tordilla Hill (ten miles northwest of Three Rivers, in Live Oak County).
In 1970, according to the United States Atomic Energy Commission, Texas uranium reserves totalled 6,622.323 tons of ore averaging 0.16 percent U3O8 based on a price of $8 per pound, giving it the country's fourth largest reserves in 1969 and third in 1970. At the same time, although drilling footage declined, Texas continued to rank second in drilling for uranium in the nation. By mid-1970 twenty-two drilling rigs and ten logging units operated from Fayette County to Starr County. Over one million acres were under lease, and eighteen major companies and independent operators were involved in leasing activities. The 1970s witnessed an upsurge in development activity, and in the mid-1970s substantial increases in uranium prices occurred. Increased demand encouraged exploration, development, and expansion of facilities throughout the decade, despite delays in nuclear plant construction and competition from foreign discoveries in Canada and Australia. Exploration for uranium concentrated on a strip ten to twenty miles wide and 200 miles long, extending from Gonzales to Duval County. Continental Oil Company (CONOCO) and Pioneer Nuclear Corporation began a venture known as the Conquista project to mine uranium and build a 1,750-ton-per-day processing mill southwest of Falls City in Karnes County. The project, requiring a labor force of 125 in all, called for mining ore by open pit methods within a thirty-five mile radius of the plant and hauling it by truck. Mining was scheduled to begin in 1971. A new Susquehanna-Western 1,000-ton-per-day uranium mill at Ray Point also began operation.
In 1975 uranium output remained unchanged from the previous year, but gained roughly 17 percent in unit value. Over 90 percent of yellowcake production came from the Conquista mill, and ore feed for the Conquista solvent-extraction mill was trucked from ten open pit mines in Karnes and Live Oak counties. Atlantic Richfield Company completed construction of its Clay West uranium recovery plant and expanded a pilot test project into the country's first commercial in situ uranium-solution mine, successfully shipping its first 30,000 pounds of uranium oxide concentrate. At the same time, the Wyoming Minerals Corporation (Westinghouse) operated pilot in situ solution mines near Bruni in Webb County and Three Rivers in Live Oak County. Dalco Oil Company and United States Steel Corporation negotiated with an electric utility and a foreign enterprise regarding sales of their Burns in situ leach facilities near George West in Live Oak County and uranium reserves in South Texas. Union Carbide Corporation constructed development wells and uranium recovery facilities at its Palangana in situ leach project north of Benavides in Duval County, and Mobil Oil Corporation continued its experimental work at its O'Hern in situ leach project near Bruni in Webb County. Total exploration and development drilling of 3.3 million feet gave the state a ranking of third in the nation, while increasing uranium prices returned an 11 percent increase in drilling activity, and land held for uranium exploration and mining decreased less than 1 percent for the year to 622,000 acres. 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. The company placed its Kingsville Dome Mine near Corpus Christi on temporary standby to develop the Rosita Project.