Historical clue formulations

• Mineral used in glass production — 2023-09-10
• Finely ground quartz — 2021-07-22
• Heat-resistant glass — 2020-10-30
• Ingredient in glassmaking — 2015-06-21
• Mineral in the form of quartz or flint — 2011-02-05
• Proctor ___ (small appliance brand) — 2010-05-09
• Glass ingredient — 2005-10-26
• Proctor-___ (small appliance maker) — 2004-01-16
• Finely ground quartz used as paint filler — 1996-06-30