Probably 99+% of all bonding wires are: pure gold, aluminum, or copper. There are a few odd-ball ones out there but they seem to be quite rare.
Of these 3:
The yellow ones are always gold. An inch is worth from 0.5 to 1 cent per inch, depending on whether they are .0007" or .001" in diameter.
The white ones are aluminum. They are worthless.
I've never seen the copper bonding wires, except in pictures.
https://www.google.com/search?q=copper+bonding+wires&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiZl8DugI7UAhVBzoMKHaHkDAYQ_AUICygC&biw=1138&bih=481