* Most abundant in the Earth's crust?

* Feldspar is the most abundant mineral, making up around 60% of the Earth's crust.

* Quartz is the second most abundant, making up about 12% of the Earth's crust.

* Other common minerals in the Earth's crust include pyroxene, amphibole, mica, and olivine.

* Most commonly found in rocks?

* The minerals listed above are all very common in rocks, along with calcite (found in limestone and marble), dolomite (found in dolostone), and gypsum (found in sedimentary rocks).

* Most commonly used by humans?

* Quartz is used in many applications, including glass, electronics, and abrasives.

* Feldspar is used in ceramics, glass, and some types of paint.

* Mica is used as an insulator in electrical equipment.

* Calcite is used in cement, building materials, and papermaking.

* Gypsum is used in drywall, plaster, and fertilizer.

So, depending on the definition of "common," there are different answers!