Minerals

What is a Mineral? Solid Solid Naturally Occurring Naturally Occurring Inorganic Inorganic Definite Crystal Structure Definite Crystal Structure Definite Chemical Formula Definite Chemical Formula

Minerals are Identified by their Physical and Chemical Properties Crystal Structure Crystal Structure Color Color Luster Luster Streak Streak Cleavage and Fracture Cleavage and Fracture Reactions with Acid Reactions with Acid Other Special Properties Other Special Properties Hardness Hardness Specific Gravity Specific Gravity

Crystal Shape the crystal shape results from the atomic arrangement into geometric patterns when the mineral forms the crystal shape results from the atomic arrangement into geometric patterns when the mineral forms

Color Usually the first and most easily observed Usually the first and most easily observed -some minerals come in many colors -color changes due to impurities or exposure to air or radiation exposure to air or radiation QUARTZROSE QUARTZSMOKY QUARTZ

Luster appearance of a mineral’s surface as it reflects light appearance of a mineral’s surface as it reflects light Metallic – look like shiny car Metallic – look like shiny car Nonmetallic Nonmetallic Glassy shine Glassy shine Muted shine Muted shine Dull shine Dull shine

Streak Color of the mineral powder Color of the mineral powder Determined by rubbing the mineral on a piece of unglazed porcelain called a streak plate Determined by rubbing the mineral on a piece of unglazed porcelain called a streak plate

Cleavage and Fracture Minerals break along lines of weakness in their crystal structure Minerals break along lines of weakness in their crystal structure Cleavage occurs when a mineral splits or cracks along flat planes Cleavage occurs when a mineral splits or cracks along flat planes Fracture occurs when a mineral breaks at random lines Fracture occurs when a mineral breaks at random lines

Reactions with Acid Minerals in the Carbonate Family (CO 3 ) react chemically with acid to produce carbon dioxide gas Minerals in the Carbonate Family (CO 3 ) react chemically with acid to produce carbon dioxide gas Reaction creates bubbles of gas and the mineral appears to fizz Reaction creates bubbles of gas and the mineral appears to fizz

Special Properties Magnetism Magnetism Taste Taste Smell Smell Fluorescence Fluorescence Phosphorescence Phosphorescence Refraction Refraction Radioactive Radioactive Electrical Electrical

Special Properties Magnetism (Magnetite) Magnetism (Magnetite) Glowing under ultraviolet light (Fluorite) Glowing under ultraviolet light (Fluorite) Salty taste (Halite) Salty taste (Halite) Smell (Sulfur) Smell (Sulfur) Reaction to HCl (Calcite) Reaction to HCl (Calcite)

Hardness a mineral’s resistance to scratching a mineral’s resistance to scratching determined by using the Mohs Scale determined by using the Mohs Scale In the field, common objects are used to determine hardness. In the field, common objects are used to determine hardness. >2 fingernail 3 penny 3 penny ~5 steel of a pocket knife 5.5 glass 6.6 steel of a file 7 quartz crystal 7 quartz crystal

Minerals in Mohs Scale softesthardest

Specific Gravity Similar to density, which is the amount of matter in a given space (Mass/Volume) Similar to density, which is the amount of matter in a given space (Mass/Volume) Determined by weighing the mineral in air and in water Determined by weighing the mineral in air and in water Dry Weight divided by Difference = specific gravity Dry Weight divided by Difference = specific gravity