It takes a special set of geologic and geochemical circumstances to concentrate a metal in economic quantities. For each of the metals in your bike, list the mineral it most commonly occurs in and briefly define and describe its most common geologic occurrence. Metal does not come out of the ground in its pure, elemental form. It is contained in various minerals, and these minerals must occur in sufficient quantity for that rock to be considered ore. The amount of metal in ore is called the grade.
Some commodities are precious enough that they can be economically mined at very low grades.
Gold, for instance, can be economic to mine at the grade of 0.05 ounces gold per ton of rock. Figure 16.2 in your text shows concentration factors for various elements. Now, calculate the size of the pile of rock that would be left over from mining the ore to make your bike. This amount is highly variable, but we can probably double our number again to try to account for this. Compare this to the amount of rock you'd have to move to produce an average gold wedding band - 2.8 tons of rock, which is 2,800 kg.