tunka -tuk- gismu

x1 is made of/contains/is a quantity of copper (Cu); [metaphor: reddish, electrical conductor].

See also jinme, lastu, ransu.

In notes:

jinme
x1 is a quantity of/contains/is made of made of metal of composition including x2.
lastu
x1 is a quantity of/contains/is made of brass [copper/zinc alloy] of composition including x2.
ransu
x1 is a quantity of/contains/is made of bronze of composition including x2.