Across
- 3. / Objects from space that create intense heat when they hit Earth
- 6. / The main material used to make human-made glass
- 9. / Early ________ experimented with making glass
- 10. / Glassy volcanic rock
- 11. / The name for glass tubes formed when lightning strikes sand
- 12. / The common essential factor in all glass formation
Down
- 1. / Sand, soda-ash and rock are examples of _______
- 2. / Natural glass created through meteorite impacts
- 4. / Special qualities or characteristics or materials
- 5. / The surroundings where something is formed or found
- 7. / To join together by heating
- 8. / Hot, melted rock from a volcano