Large deposits of limestone are found throughout northeastern Oklahoma, while gypsum is extracted in the northwest, the west-central region, and the four southwesternmost counties. Oklahoma was a leading producer of lead and zinc until the 1970s.
The value of nonfuel mineral production in Oklahoma in 2001 was estimated at $530 million, a 7.3% increase over 2000. Crushed stone continued as the state's leading mineral commodity, accounting for about 40% of the total nonfuel mineral value in 2001. Together with construction sand and gravel and gypsum it accounted for more than 50% of the total. Oklahoma remained the only state producing crude iodine, with a value of $20.9 million for the production of 1,340 metric tons. The state remained first of 20 states producing crude gypsum, with 2.65 million metric tons worth $23.3 million in 2001. It was 2nd of four states producing tripoli, 3rd in crude helium, and 5th in feldspar. The combined value of cement, feldspar, helium, lime, salt, and tripoli was $187 million. In 2001, Oklahoma ranked 31st in the US in nonfuel mineral value.