With the rebirth of the gold industry, in 1999, gold has dominated the mineral industry in Tanzania, and was expected to grow substantially in the near future. Because of significant exploration successes and government investment incentives, Tanzania's mining sector has been playing an increasingly important role in the economy. The value of output in the mining sector grew by 13.9% in 2000, 9.1% in 1999, and 27.4% in 1998—nearly doubling from 1996 to 2000, primarily because of substantial increases in diamond and gold production. GDP grew by 4.9% in 2000, 4.7% in 1999, and 4% in 1998. Mining contributed 2.3% to GDP in 2000; in 1994, mineral production accounted for 13%. Between 1995 and 2000, expenditures on exploration and mine development in Tanzania exceeded $1 billion, most of which was directed toward gold. Gold was the top export commodity in 2002, and diamond and gold mining comprised the country's second-leading industry, followed by oil refining, and the production of cement, fertilizer, and salt. Gold exports increased from $3.34 million in 1998 to $120.53 million in 2000; diamond exports, from $12.11 million to $45.75 million; gemstone exports, from $8.13 million to $18.50 million; and tanzanite exports totaled $32 million.
Output of refined gold was 15,060 kg in 2000, up from 4,767 in 1999 and 427 in 1998; output fell to less than 10 kg in 1981. With the opening of three new mines, and planned investment of $1.5 billion, gold production was expected to reach 30,000 kg in 2001 and 57,000 kg in 2007. The Geita gold mine (owned by Anglogold and Ashanti Goldfields) started production in mid-2000, produced 5,500 kg from 1.24 million tons of ore by the end of the year, and planned to produce 15,600 kg per year; Geita's total resources amounted to 90.1 million tons (4 grams per ton of gold), and total reserves, 63.6 million tons (3.8 grams per ton of gold). Barrick's Bulyanhulu gold mine was expected to start production in 2001, and planned to produce 12,400 kg per year of gold and 20,000 tons of copper concentrate by 2004; resources were 30.75 million tons containing 454,000 kg of gold, and proven and probable reserves totaled 23.37 million tons containing 311,600 kg of gold. Other gold fields included Musoma (east of Lake Victoria), Lupa (southeast of Lake Rukwa), Mpanda (east of Lake Tanganyika), the new North Mara (northwestern Tanzania), the Golden Pride Mine, Golden Ridge, Tulawaka, Nyakafuru, Kitongo, Buckreef, Rwamagaza, Miyabi, Mwagi Magi, Buhemba, and Rukwa.
Diamond output in 2000 was 354,400 carats, up from 234,800 in 1999 and 123,100 in 1997. Diamonds—85% of which were gem-quality or semigem-quality—were mined at the Williamson field, in Mwadui. The deposits were owned jointly by the government and Willcroft, of Canada. Diamond production has declined since the 1967 peak (988,000 carats), because of depletion of higher-grade ores and equipment failure. Production hit a low in 1994, 17,177 carats. Diamond resources were 114 million tons containing 6.5 million carats. The output of other gemstones (including alexandrite, amethyst, aquamarine, cat's eye, chrysoprase, emerald, garnet, opal, peridot, rhodolite, ruby, sapphire, scapolite, spinel, tanzanite, topaz, tourmaline, and zircon) was 150,800 kg in 2000, compared to 95,200 in 1999, 48,518 in 1998, and 509,489 in 1997. African Gem Resources, the new owner of block C of the Merlani mining area, estimated that block C, with resources of 2.24 million tons of ore, grading 22 carats per ton, contained two-thirds of the world's known deposits of tanzanite.
In 2000, Tanzania produced 60,000 tons of crude gypsum and anhydrite, as well as calcite, hydraulic cement, clays (including bentonite and kaolin), crushed limestone, salt, glass sand, and soda ash, and presumably stone, and sand and gravel. Resources of limestone totaled 155 million tons; marble resources for lime production totaled 137 million tons; and calcitic marble resources amounted to 121 million tons. No iron ore or graphite was produced in 1998–2000, and no phosphate minerals in 1999 and 2000. Resources and proven reserves of iron ore—in Itewe, Liganga, and the Uluguru Mountains—totaled 103 million tons. Deposits of cobalt, copper, lead, mica, nickel, phosphates, tin, titanium, tungsten, and uranium were also known to occur, and companies were exploring for cobalt and nickel and planning to produce copper concentrate from a gold mine.