Matter and Minerals

Matter and Minerals

1. Rock

   • any solid mass of mineral, or mineral-like, matter that occurs naturally; properties of rocks are determined by minerals within them
   • Mineral
     • naturally occurring inorganic solid, crystalline structure, definite chemical composition with some variation
     • Mineralogy
       • study of minerals; minerals used in everyday things; minerals are the building blocks of rocks
     • Chemical compounds
       • elements joined with atoms of other elements; most minerals are chemical compounds of atoms of two or more elements
       • when elements form compounds their properties change signifigantly
       • Element
         • Group of same kind of atoms; 90 naturally occuring
         • Atom
           • smallest particles that cannot be chemically split; have 1 to 100+ protons
           • most were created inside stars by nuclear fusion & released into space during supernova explosions
           • Nucleus
             • located within atoms; contains protons & neutrons
             • Protons (+1)
               • dense, positive electric charge
             • Neutrons (0)
               • dense, no electrical charge
           • Principle shells
             • arrangement of electrons, surrounds nucleus; each shell holds a specific amount, outermost contains valence electrons
             • Electrons (-1)
               • surrounds nucleus as a cloud; negligible mass; negative electrical charge
             • Valence electrons
               • outermost electrons; form chemical bonds with other atoms
           • Bonds
             • Chemical bond
               • the transfer or sharing of electrons that allows each atom to attain a full valence shell of electrons
               • Octet rule
                 • atoms tend to gain, lose, or share electrons until they are surrounded by eight valence electrons
             • Ionic bond
               • The attraction of oppositely charged ions to one another, producing an electrically neutral ionic compound. (NaCl)
               • When one atom gives up one or more of its valence electrons to another atom to form ions
               • When valence electrons are transferred between the elements to form ions
               • Ions
                 • Positively and negatively charged atoms
             • Covalent bond
               • a chemical bond formed by the sharing of a pair of electrons between atoms (Hydrogen molecule)
             • Metallic
               • result of an attraction between the sea of negatively charged electrons and positive ions; valence electrons are free to move throughout
               • Malleable
                 • sheets
               • Ductile
                 • wire
         • Periodic table
           • Atomic number
             • Number of protons in a nucleus
           • Mass number
             • Total number of neutrons & protons
           • Charge
             • atomic number +/- atomic number ( + negative charge, gained neutrons; - positive, lost neutrons)
         • Common elements
           • oxygen - 8 silicon - 14 iron - 26 magnesium - 12 potassium - 19 sodium - 11 calcium - 20 aluminum - 13
           • Silicon (14)
           • Oxygen (8)
       • Magma crystallization
         • Magma cools, bonds form, and crystals grow
       • Hydrothermal precipitation
         • Hot water cools off, ions exsolve and bond together to form crystals
       • Petrification
         • Buried organic matter is gradually replaced by minerals derived from groundwater
       • Evaporation
         • Causes concentration of dissolved ions to rise until bonds form and crystals grow
       • Biologic processes
         • Organisms extract ions from water and concentrate them until minerals form
       • Metamorphism
         • Cause by intense heat and pressure; Old minerals react chemically to form new minerals
       • Weathering
         • Original minerals replaced by minerals that are stable at earth’s surface; Some minerals more resistant than others
     • Properties
       • Habit
         • the common characteristic shape of individual crystal or aggregates of crystals; equant, bladed, fibrous, tabular, prismatic, platy, blocky, banded, granular, botryoidal
       • Optical
         • Luster
           • Appearance of light reflected from surface
           • Metallic
           • Non-metallic
             • Glassy, dull, pearly, silky, greasy...
         • Light transmission
           • Opaque, translucent, transparent
         • Color
           • Sometimes ambiguous and misleading
         • Streak
           • Color left on streak plate; metallic minerals generally have a dense & dark streak, non-metallic typically have light colored
       • Strength
         • Hardness
           • resistance to abrasion or scratching; numerical value of hardness: Mohs scale
         • Cleavage
           • Breakage along weak atomic bonds
         • Fracture
           • Breakage along chemical bonds that are equally strong in all directions; conchoidal, splintery, fibrous
         • Tenacity
           • Resistance to breaking, bending, cutting, etc...; brittle, malleable, sectile, elastic
       • Density
         • mass per unit volume
         • Specific gravity
           • ratio of a minerals weight to the weight of an equal volume of water; most have a specific gravity of 2 or 3 making estimating easier
       • Other
         • salt taste like salt, talc soapy, graphite greasy, sulfur smells like eggs, magnetite magnetic, calcite double refraction, carbonates fizz with HCL
     • Definition
       • Naturally occurring
         • non-synthetic
       • Generally inorganic
       • Solid substance
         • including ice, but not water; exception is mercury
       • Orderly crystalline structure
         • their atoms (ions) are arranged in an orderly, repetitive manner; reflected in crystals
       • Definite chemical composition, some variation
         • have compositions that can be expressed by a formula
     • Rock-forming
       • Silicates
         • Most common mineral group; contains silicon + oxygen
         • crystalizes from molten rock as it cools; environment + chemical composition of molten rock determine which minerals are produced
         • Some form from weathered products of other silicates
         • Structure and chemical composition indicate how it was formed.
         • Silicon-oxygen tetrahedron
           • fundamental building block of silicates; strong bonds cleave between structures
         • Light
           • Contain aluminum, potassium, calcium, and sodium.
           • Feldspars
           • Quartz
           • Muscovite
           • Clay minerals
         • Dark
           • Contain iron and magnesium
           • Olivine
           • Pyroxenes
           • Hornblende
           • Biotite
       • Nonsilicates
         • not as common; valuable uses (carbonates, sulfates, halides)
         • divided into groups based on common ions
         • Carbonates
         • Sulfates
         • Halides
         • Oxides
         • Single elements
   • Aggregate
     • Joined in a way that natural mineral properties are maintained
   • single mineral
     • limestone: impure calcite
   • non-mineral
     • non-crystalline pumice & obsidian; organic coal

2. Natural Resources

   • Renewable
     • can be replenished over relatively short spans
     • Sun
     • Ethanol
   • Non-renewable
     • though these resources form continuously, the processes to create them are so slow that significant deposits take time to accumulate
     • Iron
     • Gas
   • Mineral
     • Occurrences of useful minerals formed in such quantities that eventual extraction is certain
     • Ore deposit
       • Extracted economically; Cost of mining can sometimes exceed worth of ore mined