Mineralogy Basics

Definition and Classification

• Minerals are naturally occurring inorganic substances with a specific chemical composition and a crystalline structure.
• Classified into different groups based on their chemical composition and properties.

Types of Minerals

• Oxides: Minerals with oxygen as the anion, e.g., hematite (Fe2O3), magnetite (Fe3O4).
• Silicates: Minerals with silicon and oxygen as the main components, e.g., quartz (SiO2), feldspar (KAlSi3O8 – NaAlSi3O8 – CaAlSi3O8).
• Carbonates: Minerals with carbon and oxygen as the anion, e.g., calcite (CaCO3), dolomite (CaMg(CO3)2).
• Sulfides: Minerals with sulfur as the anion, e.g., pyrite (FeS2), galena (PbS).
• Halides: Minerals with chlorine, bromine, or iodine as the anion, e.g., halite (NaCl), sylvite (KCl).
• Native Elements: Minerals composed of a single element, e.g., gold (Au), copper (Cu), sulfur (S).
• Phosphates: Minerals with phosphorus and oxygen as the anion, e.g., apatite (Ca5(PO4)3(F,Cl,OH)).

Physical Properties

• Color: Minerals can have a wide range of colors, from transparent to opaque.
• Luster: The way a mineral reflects light, e.g., metallic, glassy, earthy.
• Streak: The color of the powder produced when a mineral is scratched on a porcelain plate.
• Hardness: A mineral's resistance to scratching, measured on the Mohs hardness scale (1-10).
• Cleavage: The way a mineral breaks or splits along flat surfaces.
• Fracture: The way a mineral breaks or splits in a non-flat surface.
• Density: A mineral's mass per unit volume.

Chemical Properties

• Chemical Composition: The proportion of elements that make up a mineral.
• Reactivity: The ability of a mineral to react with other substances, e.g., acids, water.
• Solubility: The ability of a mineral to dissolve in a solvent.

Uses of Minerals

• Construction: Minerals used in building materials, e.g., limestone, sand, gravel.
• Manufacturing: Minerals used in the production of goods, e.g., iron, copper, chromium.
• Electronics: Minerals used in electronic devices, e.g., copper, silver, gold.
• Agriculture: Minerals used as fertilizers, e.g., potassium, phosphorus.
• Jewelry and Decorative Items: Minerals used in the production of gemstones, e.g., diamonds, rubies, emeralds.