Oxygen and silicon are the two most common ELEMENTS in the Earth's crust. These two elements bond to create silicates, which are the most abundant GROUP OF MINERALS in the Earth's crust. But the most common single mineral in the crust is Quartz and as a group feldspar.
The most common mineral element in Earth's crust is Silica, in a percentage of 27 point seven percent, the second most abundant mineral is Aluminum, with an eight percent and third Iron, with a five percent.
I very much regret that the exact percentage is not known since no one has managed to find a way to find the exact mass of the earth's crust, which would probably form the denominator of such a percentage.