https://archive.cdc.gov/www_cdc_gov/niosh/docs/mining/works/coversheet132_1766767561.html
CDC - Mining - Nonmetal Operator Mining Facts - 2002 - NIOSH
Apr 6, 2022 - In 2002, a total of 763 nonmetal mining operations reported employment to the Mine Safety and Health Administration (MSHA). Examples of nonmetal mining...
cdcminingoperatorfactsniosh
https://www.wikidata.org/wiki/Q19600
nonmetal - Wikidata
chemical elements which tend to localize their valence electrons rather than forming a metallic material
wikidata