In 2005, Oklahoma mines produced both industrial minerals and coal. No metals were mined in the state. Based on value, leading industrial minerals include crushed stone followed by cement, construction sand and gravel, industrial sand and gravel, iodine and gypsum. The Oklahoma Department of Mines (ODOM) reported that more than 343 mine operators produced nonfuel minerals from 405 mines in the state. However, 530 mining permitted sites were on file. The Oklahoma Miner Training Institute (OMTI) held 239 classes for 33,768 classroom hours of instruction, in which 84 coal miners and 4,587 metal/nonmetal miners were trained.