| Answer | Crossword Clue |
|---|---|
| PERLITE | Glassy rock |
| LAVA | Glassy rock |
| OBSIDIAN | Glassy volcanic rock. |
| PITCHSTONE | Glassy volcanic rock |
| impactite | a rock, typically glassy, produced where a meteor has collided with the earth |
| impactites | IMPACTITE, a rock, typically glassy, produced where a meteor has collided with the earth |
| limburgite | a volcanic rock composed of olivine and augite in a fine-grained or glassy groundmass |
| limburgites | LIMBURGITE, a volcanic rock composed of olivine and augite in a fine-grained or glassy groundmass |
