Here's a breakdown of the approximate percentages by weight:

* Oxygen (O): 46.6%

* Silicon (Si): 27.7%

* Aluminum (Al): 8.1%

* Iron (Fe): 5.0%

* Calcium (Ca): 3.6%

* Sodium (Na): 2.8%

* Potassium (K): 2.6%

* Magnesium (Mg): 2.1%

These elements combine to form various minerals, with the most common being feldspars, quartz, pyroxenes, amphiboles, micas, and olivine.

It's important to note that the chemical composition of the crust varies depending on whether you're looking at the continental crust or the oceanic crust. The continental crust is thicker and has a higher proportion of silica and aluminum, while the oceanic crust is thinner and richer in iron and magnesium.