PUMICE

Solidified lava used as an abrasive (6)

Solution has appeared in 2 crosswords (1 across and 1 down):

• Quick crossword No 16,672 — 2023-10-11 23:00:52
  18D: Solidified lava used as an abrasive (6)
• Quick crossword No 16,166 — 2022-03-01 00:00:04
  15A: Solidified lava used as an abrasive (6)