2Matter Elements and the Periodic Table Elements are the basic building blocks of minerals. Over 100 elements are known.
3Matter Atoms Smallest particles of matter Have all the characteristics of an element The nucleus is the central part of an atom and containsprotons, which have positive electrical chargesneutrons, which have neutral electrical charges
4Matter Atoms Energy levels, or shells surround the nucleuscontain electrons—negatively charged particles The atomic number is the number of protons in the nucleus of an atom.
6IsotopesMatter Isotopes of an element have the same number of protons but varying numbers of neutrons. Have different mass numbers: the sum of the neutrons plus protons Many isotopes are radioactive and emit energy and particles. The mass number is the number of neutrons and protons in the nucleus of an atom.
7Why Atoms BondMatter When an atom’s outermost energy level does not contain the maximum number of electrons, the atom is likely to form a chemical bond with one or more atoms.A compound consists of two or more elements that are chemically combined in specific proportions.An ion is an atom that gains or losses electrons.
8Matter Types of Chemical Bonds 1. Ionic bonds form between positive and negative ions.2. Covalent bonds form when atoms share electrons.3. Metallic bonds form when metal ions share electrons.
9Minerals: the building blocks of rocks Definition of a Mineral:naturally occurringinorganicsolidcharacteristic crystalline structuredefinite chemical composition
10How do we identify minerals? Physical properties:ColorLusterHardnessCrystal shapeCleavageSpecific gravityOther
11Physical Properties of Minerals Color:Most obvious, but often misleadingDifferent colors may result from impuritiesExample:Quartz
12Physical Properties of Minerals Color:Streak – color of a mineral in powdered form(used for metallic minerals)Obtained by scratching a mineral on a piece of unglazed porcelain.Example:Hematite
13StreakRed chalk on a chalk board makes red marks. White chalk makes white marks.Not all minerals work this way. When some minerals are scratched along a ceramic streak plate, it creates a different color.
14GoldWhen gold is run across a streak plate it makes a yellowish-gold color.That makes sense.
15Pyrite or “Fool’s Gold” When pyrite is run across a streak plate, it has a black or dark green streak.Pyrite is not worth much money, while gold is worth a lot. They look alike, so miners call it fool’s gold.
16Hematite Hematite’s color is grey, but its streak is red. Hema means blood.The mineral was named hematite because it looked like it was bleeding when it was taken across a streak plate.
24Physical Properties of Minerals Hardness:How easy it is to scratch a mineralMohs Scale of Hardnessrelative scaleconsists of 10 minerals, ranked 1 (softest) to 10 (hardest)
25Mohs Scale of Hardness Hardest (10) – Diamond Softest (1) – Talc Common objects:- Fingernail (2.5)- Copper penny (3.5)- Wire nail (4.5)- Glass (5.5)- Streak plate (6.5)
26Hardness Is measured by how easy it is to scratch. Geologists order the hardness by…Scratched by a fingernail.Scratched by a penny.Scratched by a nail.Scratched by a diamond.These are not all of the tools geologists use, but it will work for our experiment.
27Gypsum is soft, it can be scratched by a fingernail.
28Calcite is soft, but a little harder because it cannot be scratched by a fingernail, but it can be scratched by a penny.
29Fluorite is harder. It can be scratched by a nail, but not a penny or fingernail.
30Diamonds are the hardest mineral, so it scratches every mineral.
31Physical Properties of Minerals Crystal shape (or form):external expression of a mineral’s internal atomic structureplanar surfaces are called crystal facesangles between crystal faces are constant for any particular mineralQuartzPyrite
32Physical Properties of Minerals Cleavage vs. Fracture:The way a mineral breaksCleavage: tendency of a mineral to break along planes of weaknessMinerals that do not exhibit cleavage are said to fractureDo not confuse cleavage planes with crystal faces! Crystal faces are just on the surface and may not repeat when the mineral is broken.
33Physical Properties of Minerals Cleavage is described by:Number of planesAngles between adjacent planesThese are constant for a particular mineral
34Physical Properties of Minerals Cleavage (1 direction):Example: mica
41Physical Properties of Minerals Specific gravity:weight of a mineral divided by weight of an equal volume of watermetallic minerals tend to have higher specific gravity than non-metallic mineralsGalenaSG=7.5QuartzSG=2.67
42Physical Properties of Minerals Other properties:reaction with hydrochloric acid (calcite fizzes)taste (halite tastes salty)feel (talc feels soapy, graphite feels greasy)magnetism (magnetite attracts a magnet)
43Mineral Groups Rock-forming minerals ~30 common minerals make up most rocks in Earth’s crustComposed mainly of the 8 elements that make up over 98% of the crust
44SILICATES Mineral Groups Common cations that bond with silica anions Element AbundancesSilica(SiO4)4-SILICATESCommon cations thatbond with silica anionsAll others: %
45Mineral Groups Silicates (most abundant) Non-silicates (~8% of Earth’s crust)Oxides O2-Carbonates (CO3)2-Sulfides S2-Sulfates (SO4)2-Halides Cl-, F-, Br-Native elements (single elements; e.g., Au)
46Mineral Groups Non-ferromagnesian Silicates (K, Na, Ca, Al) Silicates (Fe, Mg)OxidesCarbonatesSulfides/sulfatesNative elements
47Mineral Groups – Silicates Tetrahedronfundamental building block4 oxygen ions surrounding a much smaller silicon ionSilicon-oxygentetrahedron(SiO4)4-
48Mineral Groups – Silicates Joining Silicate StructuresHow tetrahedra may be linked:independent tetrahedrasingle chainsdouble chainssheets3-D framework
50Mineral Groups – Silicates Olivine Groupdark silicates (Fe-Mg) ferromagnesianNo cleavage
51Mineral Groups – Silicates Pyroxene GroupFerromagnesian / dark silicates (Fe-Mg)Augite2-directionsof cleavage(at nearly 90 degrees)
52Mineral Groups – Silicates Amphibole GroupFerromagnesian / dark silicates (Ca, Fe-Mg)Hornblende2-directionsof cleavage(not at 90 degrees)
53Mineral Groups – Silicates Mica Group and Clay Mineralslight silicates (K, Al) non-ferromagnesianMuscovite1-directionof cleavage
54Mineral Groups – Silicates Feldspar Grouplight silicates (K-Na-Ca, Al)K-feldsparMost common mineral groupOrthoclasePlagioclase2-directionsof cleavage(at 90 degrees)Ca/Na-feldspar
55Mineral Groups – Silicates Quartzlight silicates (pure SiO2)no cleavage(conchoidal fracture)hard, resistant to weatheringQuartz
56Minerals Mineral Groups 2. Carbonates 3. Oxides Minerals that contain the elements carbon, oxygen, and one or more other metallic elements3. OxidesMinerals that contain oxygen and one or more other elements, which are usually metals
57Minerals Mineral Groups 4. Sulfates and Sulfides 5. Halides Minerals that contain the element sulfur5. HalidesMinerals that contain a halogen ion plus one or more other elements6. Native elementsMinerals that exist in relatively pure form