There are four parts to this answer. These are:

1. There are about seventeen minerals on Earth's surface that are really common, and these account for most of the Earth's material and most of the common elements.

2. There are a lot of different proportions in which you can plug familiar elements together.

3. Even with the same proportions, there are a lot of different ways to shape a crystal lattice. Calcite and aragonite, for example, are both calcium carbonate, but they have a different crystal structure and thus are different minerals.

4. Of the approximately three thousand minerals that are rare, you have the other approx. seventy elements to play with to build them.

Yes about 3000... Yes all minerals of course are made up of one or more of the naturally occurring elements numbering about 92.There are about 20 to 30 "common" minerals. The elements in these common minerals are Si, Al, O, Fe, Mg ,K, Ca, Na mainly. Then in the ore minerals in addition Cu, Ni, Cr,Zn, and many of the other metals.

The other anions are Cl, F, Phosphate group, sulphate groups, borates, and others.

Not just minerals... *everything* is made from basic atoms. The most common minerals are those made from the most common elements Earth's crust: oxygen (47%), silicon (28%), aluminum (8%), iron (5%),calcium, sodium, potassium, magnesium... Quartz and feldspar are two examples of minerals made mostly with oxygen and silicon.