| Clue | Source | Date |
|---|---|---|
| Rock composed of volcanic dust (4) | ||
| Hard-sounding volcanic rock (4) | ||
| A light porous rock sounds tough | Irish Times Crosaire | 31 Dec 2021 |
| Volcanic rock | ||
| '— Enuff' (1986 top 10 hit) | Premier Sunday | 20 Jan 2019 |
| Volcanic rock | ||
| Porous rock. | ||
| Volcanic rock. | ||
| Stratified volcanic rock. |