(4) slate because it is the strongest
If you melt and cool silicon dioxide under very special conditions
<span>in the laboratory we can grow a single </span>crystalline<span> form of </span>
<span>silicon dioxide that we call quartz. In quartz crystals all of </span>
<span>the molecules are aligned and bonded together in a regular three </span>
<span>dimensional tetrahedral structure forming a very hard, transparent </span>
<span>material with special electronic properties. </span>
I would say "Greek myths"