I am going to gamble with Quartz as the material is just the same... As zinc is used to make batteries, It has to be quartz hands down.
Explanation:
1. K (Potassium)
2. Te (Tellurium)
3. F (Flourine)
4. group 11, period 4
5. group 18, period 4
6. group 12, period 6
7. Cl
8. Pb
9. W
10. Sb
11. Na
12. period 6, group 11
13. period 5, group 11
14. period 2, group 16
15. Groups 13–16 of the periodic table contain one or more metalloids
16. Hydrogen
17. Helium
18. Calcium
19. Cobalt
20. Carbon
A bridge must be made of metal or concrete or other materials that are strong enough to withstand the forces of the traffic passing over it. I doubt that the material could do that.
If the substance is a metal foam, it would make a rather hard cushion.
If the substance is too soft, it would make a cushion.
If the substance has the right combination of softness and elasticity so that it returns to its original shape when you get up, it might be a good material for a cushion.
The other substance containing sodium would be expected to make the cushion is NaClO or the Sodium hypochlorite. It is for all intents and purposes and synthetically particular from chlorine. Sodium hypochlorite is much of the time utilized as a disinfectant or a blanching operator.
