Minerals: Building Blocks of Rocks Definition of a mineral Natural Inorganic Solid Possess an orderly internal structure of atoms Have a definite chemical composition Rock – any naturally occurring solid mass of mineral or mineral-like matter

Rocks are Aggregates of Minerals

Atoms: Building Blocks of Minerals Smallest particles of matter

Atomic Structure Nucleus – central part of an atom that contains Protons – positive electrical charges Neutrons – neutral electrical charges Electron shells Surround nucleus Contain electrons – negative electrical charges

Atomic Structure

Atoms Atomic number Ions Number of protons in an atom’s nucleus. Positively or negatively charged atoms due to electron gain or loss

Composition and Structure of Minerals Elements Basic building blocks of minerals Over 100 are known Defined by their number of protons Groups of the same type of atoms

Periodic table of the elements

Atomic Bonding Valence shell Octet rule Chemical bond An atom’s outermost shell Octet rule Atoms gain, lose, or share electrons until their valence shells have 8 electrons Chemical bond Transfer or sharing of electrons to achieve full valence shell

Atomic Bonding Ionic bond Atoms bond together when oppositely charged ions attract

Atomic Bonding Covalent bond Sharing of a pair of electrons between atoms

Atomic Bonding Metallic bond Packed metal atoms have valence electrons free to move throughout the structure.

Minerals Physical properties of minerals Habit – common crystal shape Luster – appearance in reflected light Color Streak – color of mineral in powdered form Hardness – ability to resist scratching or abrasion Cleavage – tendency to break along planes of weak bonding

Metallic Luster: Galena

Color Color can be unreliable due to variations.

Streak

Crystal Shape, or Habit: Pyrite

Hardness: Mohs Scale

Cleavage: Micas

Minerals Physical properties of minerals Fracture – random pattern of breakage Specific gravity – mineral density Tenacity – resistance to cutting, breaking, bending, and deformation

Conchoidal fracture

Minerals Other properties Taste Smell Elasticity Malleability Double refraction Magnetism Feel Reaction with hydrochloric acid

Mineral Groups Rock-forming minerals Only a few dozen Most abundant atoms in Earth’s crust are oxygen (46.6% by weight) and silicon (27.7% by weight)

Mineral Groups Eight elements compose most rock-forming minerals: oxygen (O), silicon (Si), aluminum (Al) iron (Fe) calcium (Ca) sodium (Na) potassium (K) magnesium (Mg)

Composition of Continental Crust

Mineral Groups Rock-forming silicates Most common mineral group Contain the silicon-oxygen tetrahedron Four oxygen atoms surrounding a much smaller silicon atom Combines with other atoms to form the various silicate structures

Mineral Groups Rock-forming silicates Groups based upon tetrahedral arrangement Olivine – independent tetrahedra Pyroxene group – tetrahedra are arranged in chains Amphibole group – tetrahedra are arranged in double chains

Hornblende: An Amphibole

Mineral Groups Rock-forming silicates Groups based upon tetrahedral arrangement Micas – tetrahedra are arranged in sheets Two types of mica are biotite (dark) and muscovite (light) Feldspars – Three-dimensional network of tetrahedra

Mineral Groups Rock-forming silicates Groups based upon tetrahedral arrangement Feldspars – most abundant group of minerals in Earth’s crust Quartz – three-dimensional network of tetrahedra

Potassium feldspar

Rose Quartz

Mineral Groups Nonsilicate minerals – major groups Oxides Sulfides Carbonates Halides Native elements

Common Nonsilicate Mineral Groups

Minerals Mineral groups Nonsilicate minerals Carbonates A major rock-forming group Found in the rocks limestone and marble Halite and gypsum are found in sedimentary rocks Many have economic value

Natural Resources Renewable Nonrenewable Can be replenished in relatively short time spans Corn, wind, water, etc. Nonrenewable Earth has fixed quantities Oil, aluminum, natural gas, coal

Natural Resources Mineral resources Mineral resources are occurrences of useful minerals that will eventually be extracted Ore deposits are concentrations of metallic minerals that can be mined at a profit Economic factors may change and influence a resource

Copper Mining