What is It What are Minerals? Minerals are the building blocks of rocks. Mineralogists use the criteria to determine whether a material is classified as a mineral or not. Characteristics of Minerals 1. naturally occurring- term which identifies mineral as part of earth's natural processes. 2. inorganic- means a substance is not a product of an organism. 3. homogeneous solid- minerals should have definite volume and rigid shape 4. definite chemical composition-represented by a chemical formula 5. orderly crystalline structure-atoms of minerals are arranged in an orderly and repeating pattern​