Historical clue formulations

• With 34-Across, sequestration of a greenhouse gas — 2026-08-05
• Graphite, essentially — 2025-03-06
• Exact replica — 2025-03-06
• Diamond, essentially — 2011-04-19
• Coal, essentially — 2006-12-06
• Graphite element — 2004-08-31
• It can help you get a date — 2002-11-12
• Kind of copy — 1997-08-21