USGS1967
Fifty-eight mineral prospects of base metals (copper, lead, zinc), iron, manganese, gold, limestone (cement grade), barite, gypsum, and salt were investigated by geological, geophysical, and geochemical surveys, and by pitting, exploratory mining, and diamond drilling from January 1963 to May 1966. Fifty-six of the prospects are in the Loei-Chiengkarn area of northeast Thailand where regional geological, aeromagnetic, and geochemical studies were also performed; the other two prospects are on the Khorat Plateau. The base-metal prospects are in volcanic or carbonate rocks. Four prospects have been tested by diamond drilling; disseminated copper deposits were found at two prospects and local lead-zinc mineralization at the other two.The two copper deposits have estimated proven and probable reserves of 16million tons containing about 1 percent copper, and possible reserves of 62 million tons. The iron prospects are mostly metasomatic, at contacts of granodiorite with sedimentary and volcanic rocks. Four of the iron prospects were tested by diamond drilling; proven, probable, and possible reserves of about 27million tons containing 52 percent iron were developed predominantly in two deposits. Twelve manganese and two gold prospects were investigated, but all are small or low grade. Nonmetallic deposits of barite, gypsum, and limestone (cement grade) were examined in the Loei-Chiengkarn area, and salt was studied at Chaiyaphum. Reserves of approximately 5.5 million tons of barite, half a million tons of gypsum, 12 million tons of limestone (cement grade), and 2,000 million tons of salt were estimated to be present. Economic development of these deposits must await recommended economic feasibility studies and additional geological work, including diamond drilling.