[isaacg]

In particular, copper smithing predates glassmaking, 10000 years ago versus 4000 years ago

[tetromino_]

Copper melts at 1085 C, cast iron at 1200 C, steel at a bit under 1400 C, glass at well over 1400 C.

My guess is that glass was discovered by someone trying to invent steel making.

[hinkley]

Crucible steel.