eli5: Why does sand which is a bunch of tiny rocks, turn into glass, but we can’t turn big rocks into glass?

Question

I’m very tired. Please help me understand this.

In: Other

Answer 1

sand is usually all quartz, rocks contain other stuff that hasn’t been withered away yet. you just want the quartz. but even if you had a pure quartzite rock, you’d rather take sand because just like how a big block of ice melts faster if you smash it apart, melting big rocks is a bother.