Inorganic chemicals are substances of mineral origin that do not contain carbon in their molecular structure. There are several basic types of products. Examples include naturally-occurring minerals, metals and their alloys, compounds that contain non-metallic elements, and metal complexes. Inorganic chemistry, the scientific discipline devoted to the study of inorganic chemicals, has developed inorganic chemical compounds such as inorganic fertilizer compounds, inorganic phosphates, and inorganic pigments. An inorganic fertilizer compound is designed for agricultural applications and typically contains a mixture of nitrogen, phosphorous, and potassium. In a biochemical setting, an inorganic phosphate is a free-phosphate ion in solution. An inorganic pigment is used to color plastics. Inorganic synthesis, the process of synthesizing inorganic chemical compounds, is used to produce many inorganic chemicals.