Tin and gypsum mining were the country's leading industries in 2002, and tin was its fifth-leading export commodity. The mining sector, the economy's smallest, contributed 0.56% of the country's GDP in 2000. Although much of the country remained unprospected, the nature of the terrain has led to ardent speculation about the nation's mineral resources. Laos was fairly rich in gold, gypsum, iron ore, limestone, potash, precious stones, and tin; of those, only gypsum, limestone, and tin were mined. Also produced in 2001 were barite (all of which was exported to Thailand), cement, gemstones, rock salt, sand and gravel, varieties of stone, and zinc (all of which was exported to Thailand). Other mineral resources known to exist in Laos were magnesium, antimony, copper, lead, manganese, pyrites, silver, and sulfur. Copper, gemstone, gold, iron ore, lead, potash, tin, and zinc were earmarked for further exploration. Undiscovered resources of iron ore, potash, and rock salt were believed to be substantial.
Tin mine output in 2001 was 400 tons, down from 717 in 1997 and 906 in 1996. Gypsum production, by the State Gypsum Mining Operation from the Dong Hene Mine, in Savannakhet Province, was 150,000 tons in 2001, up from 114,306 in 1997; the mine's proven ore reserves were estimated to be 18 million tons. Gold production ceased in 1998–2001; it was 24,755 grams in 1997. Important iron deposits, with reserves of 68% ore estimated at 11 billion tons, have been discovered on the Plain of Jars near Xiangkhoang. A substantial deposit of low-grade anthracite coal has been found at Saravan. Sapphire production went from 4,006 carats in 1996 to 9,229 carats in 1997, and increased substantially further in 1998 and 1999. Output of gemstones went from 4,013,280 carats in 1999 to 100,000 in 2001. Tungsten and copper deposits and gold-bearing alluvials produced a limited income for the local population but have not been exploited by modern industrial methods.