1. Feldspars and quartz make up more than 50 percent of the earth’s crust.

2. In silicate minerals, bonds may form between the oxygen atoms in the tetrahedron and other elements outside the tetrahedron.

3. A mineral is any solid, crystalline substance that occurs naturally.

4. Cleavage is important in identifying some minerals.

5. The conditions under which minerals are produced usually allow single crystals to grow.

6. Sulfates and sulfides are types of nonsilicate minerals.

7. Nonsilicate minerals can contain elements such as carbon, gold, and iron.

8. Fluorite (CaF2) is an example of a nonsilicate mineral.

9. Plagioclase feldspar may contain sodium, calcium, or both.

10.Feldspars are minerals composed of atoms of silicon (Si), oxygen (O), and a metal.

11.Sphalerite (ZnS) is a sulfate mineral.

12.Silicate minerals make up more than 90 percent of the earth’s crust.