Historical clue formulations

• Underground workers — 2020-02-27
• Rock experts? — 2019-11-05
• UTEP team — 2018-05-13
• Ones taking a lode off? — 2017-02-25
• Gold diggers — 2012-08-30
• The Seven Dwarfs, by profession — 2006-06-18
• Vein specialists — 2003-12-28
• Low-level workers? — 2003-07-20
• Workers with headlights? — 2001-08-03
• Lightheaded people? — 1999-11-27
• They go for the gold — 1999-05-23
• They're given the shaft? — 1998-05-08