Firmographics.org

Code	Title	Count
2111	Oil and Gas Extraction
211120	Crude Petroleum Extraction	1590
211130	Natural Gas Extraction	565
2121	Coal Mining
212114	Surface Coal Mining	230
212115	Underground Coal Mining	138
2122	Metal Ore Mining
212210	Iron Ore Mining	43
212220	Gold Ore and Silver Ore Mining	457
212230	Copper, Nickel, Lead, and Zinc Mining	124
212290	Other Metal Ore Mining	161
2123	Nonmetallic Mineral Mining and Quarrying
212311	Dimension Stone Mining and Quarrying	58
212312	Crushed and Broken Limestone Mining and Quarrying	114
212313	Crushed and Broken Granite Mining and Quarrying	35
212319	Other Crushed and Broken Stone Mining and Quarrying	137
212321	Construction Sand and Gravel Mining	550
212322	Industrial Sand Mining	68
212323	Kaolin, Clay, and Ceramic and Refractory Minerals Mining	33
212390	Other Nonmetallic Mineral Mining and Quarrying	137
2131	Support Activities for Mining
213111	Drilling Oil and Gas Wells	730
213112	Support Activities for Oil and Gas Operations	4735
213113	Support Activities for Coal Mining	55
213114	Support Activities for Metal Mining	123
213115	Support Activities for Nonmetallic Minerals (except Fuels) Mining	58