Minerals are best described as which of the following?

• A. A naturally occurring inorganic solid with a crystal structure.
• B. A class of nitrogenous organic compounds consisting of amino acids.
• C. A large group of organic compounds including sugars and starch.
• D. A type of lipid that stores energy.

Answer: (A)

Minerals are substances formed by natural geological processes that are solids with a definite chemical composition and a crystal lattice. This combination—natural origin, inorganic composition (not from living matter), a solid state, and an orderly, repeating arrangement of atoms—defines a mineral. Organic options like amino acids, sugars and starch, or lipids describe carbon-based molecules produced by living systems, and they don’t have the same rigid, repeating crystal structure that minerals possess. The crystal structure gives minerals consistent, recognizable properties such as specific shapes, cleavage, and hardness, which helps distinguish them from organic compounds. So the description that fits best is a naturally occurring inorganic solid with a crystal structure.