Geology Test 1: Earth Materials aka Minerals – Flashcards
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Earth Materials
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Earth is made up of a suite of components-- rocks and minerals--minerals are building blocks for rocks
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Start small and move your way up in earth materials
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1. atoms, elements and atomic bonds 2. minerals 3. rocks- rock cycle
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Atom
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composed of protons, neutrons and elections; the number of each is specific to an element
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Atomic bonds
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combine elements to each other, forming minerals
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Nucleus
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composed of protons and neutrons
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Atomic Number
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# of protons
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Atomic Mass
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# of protons+# of neutrons -number of protons is constant, neutrons will vary
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Electrons
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-cloud surrounding the nucleus -#of electrons=# of protons -grouped in shells -can be donated or shared for elements to become more stable
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Rows in Periodic Table
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number of electron shells
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Columns in Periodic Table
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number of electrons in outermost shell-- ATOMS WANT TO FILL OUT THEIR SHELL- TO BE MORE STABLE
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Loss/Gain of Electrons= Ions
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depending on where they sit on the periodic table some elements can gain or lose an electron to fill the outer electron shell--creating an anion
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4 types of Chemical Bonds
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1. Intermolecular Forces 2. Metallic Bonds 3. Ionic Bonds 4. Covalent Bonds --type of bond in a mineral is determined by how many electrons are shared between the different elements
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Intermolecular Forces
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-weakest type of bond -due to polarity of molecules (bonded combinations of atoms) example; connecting sheets in micas or clays
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Metallic Bonds
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-weak bond -electrons are shared by many atoms -material help together non-ridgedly--pliable metals
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Ionic Bonds
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-moderately strong -atoms will lose or gain an electron (electrons are loaned)-- form the attraction of cations and anions
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Covalent Bonds
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-strongest type of bond -electrons are shared--minerals tend to be hard and not break very easily
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Summary of Atoms
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-atoms are building blocks of minerals -atoms form molecules -molecules form minerals
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What is a Mineral?
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-solid -inorganic naturally occurring -specific chemical composition -specific, ordered crystal/internal structure
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Minerals; Solid
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not a liquid, not gaseous -ice is a mineral but water is not
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Minerals: Inorganic
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-not a byproduct of an organic process -lacking carbon-hydrogen bonds
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Minerals: Naturally Occurring
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-found in nature -not synthesized in a laboratory
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Minerals: Chemical Composition
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-homogenous with a specific chemical composition -always the same chemical formula
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Minerals; Crystal Structure
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-ordered internal crystal structure -atoms and molecules arranged in a specific way
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Mineral Characteristics
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-crystal shape of habit -color -luster -cleavage or Fracture
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Crystal Shape/Habit
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-minerals have specific crystal shapes -only seen when allowed to grow in uninterrupted space -due to the arrangement of the atoms -cubes, prisms, sheets, needles, etc.
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Mineral Color
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Can be a very useful indicator if the mineral has a specific color; sulfur, cinnabar, malachite, pyrite BUT one mineral can have several colors -some colors are common for minerals (calcite, quartz, plagioclase
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Mineral Luster
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-the way the surface of a mineral interacts with light -pearly(like a pearl) -metallic(like tin foil) -vitreous(like glass) --quartz, pyrite, muscovite
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How minerals break
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-based on bonding -no cleavage= fractures
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Fracture
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-when a mineral does not break in a regular way-- occurs because all of the bonds are the same strength
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One Plane Cleavage
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-one plane breaks into sheets
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Two Plane Cleavage
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-two planes at 90 degrees -if not at 90 degrees; typically 60 and 120
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Three Plane Cleavage
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-three planes- 90 degrees cubic
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Mineral Characteristics Tests
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-hardness -streak -reaction with HCI -magnetism
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Mineral Hardness
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-comparative scale from 1-10 -Moh's Hardness Scale
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Mineral Streak
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-the color of the powdered mineral -no matter the color of the mineral, the streak will always be the same -may not match the color of the mineral exp: hematite, galena
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Reaction with HCI
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-when HCI is dropped onto the mineral it will fizz -characteristic of carbonate minerals; Calcite
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Magnetic Minerals
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-some iron rich-minerals (magnetite) are magnetic
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Where do minerals come from?
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-The Earth! -Magnesium is abundant in metal -silicon third most abundant element -oxygen it the most abundant element
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Silicate Minerals
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typically composed of one silicon atom bonded to four oxygen atoms -negatively charges Sio4(-4) -forms a tetrahedron
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Silicate Minerals
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silica tetrahedron have a negative charge, allowing them to bond with other tetrahedra or to other elements
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Common Silicate Minerals
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-linked tetrahedrons -via oxygen -gives us many types of silicates single chain; augite double chain; hornblende frameworks; feldspar sheets; mica
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Common, Non-silicate Minerals
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-carbonates-calcite -oxides-hematite -sufides-galena
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Hydrogen Bonding
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-like ionic bonds (opposites attract) -much weaker -not due to loss/gain of electrons--location of shared electrons -gives water its unique properties
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Water and Minerals
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-water can dissolve minerals -especially ones with weaker bonds (ionic) -wter surrounds individual cations and anions
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Major Rock-Forming Minerals
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-there are several minerals that are the main building blocks of rocks -mostly silicates (light and dark color) -carbonates -oxides -sulfides
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Silicates--light color
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1. Quartz-fracture and lots of colors 2. Muscovite Micas-one plane of cleavage and white 3. Feldspars (plagioclase and orthoclase)-two planes of cleavage (@ 90) and white, pink
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SIlicates-- Dark Color
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4. Biotite-one plane of cleavage and brown 5. Augite(Pyroxene)-two planes of cleavage and dark green to black 6. Horneblende (Amphibole)- two planes of cleavage and black 7. Ovaline- fracture and green to back
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Carbonate
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calcite- 3 planes of cleavage, white to clear, reacts with HCI
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How are minerals formed?
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-originally come from magma or lava -dissolution and precipitation
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How do we tell the difference between a rock and a mineral?
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-minerals are homogeneous -rocks are composed of one or more types of minerals
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Mineral v. Clast
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mineral crystals; naturally occurring, inorganic substance with a homogeneous composition clasts; fragments of pre-existing rocks or minerals -minerals can be organized in rocks to form layers and bands
