Both Uses of

bronze
in
Moby Dick

His whole high, broad form, seemed made of solid bronze, and shaped in an unalterable mould, like Cellini's cast Perseus.
Chpt 28-30 *

bronze = a brownish metal

Of modern standers-of-mast-heads we have but a lifeless set; mere stone, iron, and bronze men; who, though well capable of facing out a stiff gale, are still entirely incompetent to the business of singing out upon discovering any strange sight.
Chpt 34-36

bronze = made of a brownish metal

Definitions:

(1) (bronze as in: bronze won't corrode in salt water)
a brownish-colored metal with red or yellow hues that is made of copper and (usually) tin

Bronze metals in the Olympics and many other contests are awarded for third place.

With the discovery of bronze (about 3,000 BC), people could make tools and weapons that were harder and more durable than those made of copper and stone that preceded bronze.
(2) (bronze as in: a bronze tan)
a reddish-brown or yellowish-brown color like that of one of the metals with the same name -- often used to refer to a suntan or a dark glowing complexion
(3) (bronze as in: her bronze is on display)
something made of the brownish metal with the same name -- such as a sculpture (statue) or a third place medal