... coring crowns, electric coal drill bits, coal cutting picks, oil cone bits and scraping knife bits, usd in geological prospecting, coal ... 5For coring crowns, electric coal drill bits, coal cutting picks, cone drill bits and scraping knife bits, used in geological prospecting, coal ... 4260087.0Largely for the inserts and buttons of percussion bits and tricone bits to cut medium-hard, hard, and very hard ...