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83 Cards in this Set
- Front
- Back
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What are the 2 most dominant elements in the universe and how did they form?
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When rocks solidify from magma, they incorporate small amounts of water. Cooling and subsequent reactions leads to the production of peroxy links (consisting of oxygen and silicon atoms) and molecular hydrogen in the rocks. Then, when the igneous rock is subsequently weathered, the peroxy links produce hydrogen peroxide, which decomposes into water and oxygen. Simply weathering igneous rocks is a source of free oxygen into the atmosphere.
Silicon is present in the sun and also in meteorites and came to Earth when it was being bombarded by planetesmals and meteors at its formation. |
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What are the 4 most common elements in the Earth as a whole and the 8 most common elements in the Earth’s crust?
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4 Most Common in Earth as a Whole:
Fe, O, Si, Mg 8 Most Common in the Earth’s Crust: O, Si, Al, Fe, Ca, Na, K, Mg |
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How and why does the percentage of iron vary from the whole Earth to the crust?
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Most of the iron in the Earth as a whole is contained in the Core (34.6%), while only 5% is contained in the Earth’s Crust. The Crust mostly consists of a “sea of Oxygen”.
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What is a mineral?
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A naturally occurring inorganic crystalline solid with a definite chemical compound that is stable at room temperature.
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What is a synthetic mineral?
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An inorganic crystalline solid with a definite chemical compound that is stable at room temperature and is made in a lab.
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What is a mineralloid?
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A substance that has all the characteristics of a mineral but could not have correct chemical structure, or be amorphous.
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What is a mineral group?
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Groups of minerals that are classified by their crystal structure or chemical composition.
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What is a mineral species?
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A single mineral that has unique chemical and physical properties.
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What is a mineral series?
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Minerals that have end member mineral species with intermediate compositions.
I.e. Forsterite the Fayalite |
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What is a mineral variety?
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Variations on mineral species based on external physical characteristics.
I.e. Ruby, sapphire = Corundum |
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Why are silicates the most common mineral group?
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27.7% of the Earth’s Crust is made up of Silicon and so the most common types of rocks would be quartzes and feldspars. Both weather into different types of sediment, and even some foraminifera make their shells of silica which also can be broken down and added to sediment and subsequently metamorphosed.
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Why are feldspars the most common silicate group in the crust?
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Feldspars make up 60% of the Earth’s crust. They can form from magma deposits, become metamorphosed, and make up a large part of some sedimentary rocks. They also weather into clays.
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What are native minerals?
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Any mineral that contains one native element constituent, like gold, silver, iron, copper, etc.
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What are oxides?
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Non complex minerals containing oxygen or hydroxide; also contain mostly ionic bonds and this helps distinguish members from the more complex mineral classes whose bonds are typically more covalent in nature.
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What are sulfides?
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A mineral containing sulfide (S2-) as the major anion. Sulfides are economically important as metal ores.
I.e. Chalcocite, Bornite |
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What are sulfates?
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Minerals that consist of a central sulfur atom surrounded by four equivalent oxygen atoms in a tetrahedral arrangement; cation + sulfur.
I.e Pyrite (FeS) |
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What are halides?
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Any mineral where there is a cation and a halogen (Fluorine, Chloride, Iodine).
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What are carbonates?
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Minerals that contain the carbonate ion.
I.e. Calcite, Dolomite |
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What are phosphates?
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Those minerals that contain the tetrahedrally coordinated phosphate (PO43-) anion along with freely substituting anions.
I.e Apatite |
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What are silicate minerals?
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When Silicon and Oxygen are bonded together in various proportions and can be further divided into different crystal structures.
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What are tectosilicates?
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Framework silicates; have complex 3D sharing of silica tetrahedral.
I.e. Quartz, Feldspars, Zeolites. |
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What are phyllosilicates?
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Sheet silicates; have layers of bonded silica tetrahedral.
I.e. Serpentine, Talc, Muscovite, Biotite, Chlorite, clay minerals. |
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What are cyclosilicates?
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Ring silicates; have corner-sharing rings of silicate tetrahedral.
I.e. Tourmaline, Beryl |
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What are inosilicates?
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Chain silicates; have silica tetrahedral forming single or double chains (corner sharing).
I.e. Pyroxenes, Amphibole. |
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What are sorosilicates?
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Disilicates; have tetrahedral pairs.
I.e. Epidote |
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What are orthosilicates?
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Nesosilicates; have individual tetrahedral with intervening cations.
I.e. Olivine, Garnet, Aluminum Silicates, Staurolite |
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What are mineral polymorphs?
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Minerals that have different crystal structures but same chemical composition.
I.e. Calcite = Aragonite |
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What are isostructural minerals?
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Minerals that have the same type of crystalline structure.
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What is meant by crystal ‘nucleation’?
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A nucleation site is where crystals form. “Baby” crystals form in sites with a fast melt and are very unstable. As the melt cools the crystals grow and solidify.
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What controls crystal size in a solidifying magma or other rock system in which minerals are growing and why?
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If you have a fast melt, more crystal embryos will develop and compete for space. You will then have smaller crystals when the melt cools.
If you have a slow melt, you’ll have much bigger crystals that have had time to develop and didn’t compete for ions and can reach critical size. Critical size is the point at which a nucleation site will start growing as a crystal. |
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What is mineral exsolution and why does it occur?
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Exsolution is segregation, during cooling, of a homogeneous solid solution into two or more different solids.
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What characteristics are typical of ionically bonded minerals?
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An ionic bond is created when electrons pass between atoms creating cations (positively charged ions) and anions (negatively charged ions). Ions of opposite charge attract each other. The attracting force is equal in all directions and increases as the distance between the ions decreases. The ions therefore tend to pack together into a lattice whose shape is determined by the sizes, and therefore packing, of the ions involved.
Ionically bonded crystals typically display moderate hardness and specific gravity, rather high melting points, and poor thermal and electrical conductivity. I.e. Mica |
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What characteristics are typical of covalently bonded minerals?
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A covalent bond is created when two atoms share outer shell electrons so that the electrons orbit around both atoms giving each a full complement of electrons in its outer shell. In a covalent bond no electrons are given up or acquired so no ions are formed. A covalent bond is therefore possible between two atoms of the same type and is the means by which molecules are formed.
Minerals bonded in this manner display general insolubility, great stability, and a high melting point. Crystals of covalently bonded minerals tend to exhibit lower symmetry than their ionic counterparts because the covalent bond is highly directional, localized in the vicinity of the shared electrons. |
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What characteristics are typical of metallically bonded minerals?
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The outer electrons of metals are only loosely attracted to the nucleus and are therefore easily detached. The resulting metal cations tend to cluster together with the detached electrons surrounding the cations as an anionic cloud.
Metals display high plasticity, tenacity, ductility, and conductivity. Many are characterized by lower hardness and have higher melting and boiling points than, for example, covalently bonded materials. |
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What is Pauling’s 1st of Rule of Ionic Bonding?
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1. A coordinated polyhedron of anions is formed about each cation, the cation-anion distance determined by the sum of ionic radii and the coordination number by the radius ratio.
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What is Pauling’s 2nd of Rule of Ionic Bonding?
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2. For stable structures, total strength of the valency bonds for an anion is equal to the charge of the anion and its bonding capacity proportional to its oxidation state.
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What is Pauling’s 3rd of Rule of Ionic Bonding?
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3. The presence of shared edges, and particularly shared faces decreases the stability of a structure. This is particularly true for cations with large valences and small coordination number (CN).
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What is Pauling’s 4th of Rule of Ionic Bonding?
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4. In a crystal containing different cations those with large valence and small CN tend not to share polyhedral edges or faces.
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What is Pauling’s 5th of Rule of Ionic Bonding?
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5. The number of elemental constituents in a crystal tends to be small.
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How do the relative sizes of anions and cations influence coordination of atomic elements in a crystal?
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As you increase coordination number, the crystal radii increase (Pauling’s Rule #1). Then cation-anion attraction is increased because the distance between them is decreased (Pauling’s Rule #3).
Cations need to be as far away from each other as possible, otherwise they will repel each other. So they will arrange themselves as far apart as possible. The only way to do that is to share corners. If they share edges or faces, they bond becomes very unstable because they are repelling each other. |
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What is an ore?
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A concentration of elements or mineral resources that can be extracted for a profit using known techniques.
I.e. Gangue, spoils, tailings. |
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What is a mineral resource?
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A concentration of elements or mineral resources by geologic processes.
I.e. Oil, oil shale, gas, coal, uranium, geothermal. |
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What are the major minerals included in base metals?
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Copper, Lead, Zinc, Nickel, Aluminum, Antimony, Arsenic, Bismuth, Chromium, Cobalt, Iron, Manganese, Mercury, Molybdenum, Sodium, Sulfides, Titanium, Tungsten, Vanadium.
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What are the major minerals included in precious metals?
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Gold, Silver, Platinum, Palladium, Ruthenium, Rhodium, Osmium, Iridium.
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What are the major minerals included in clay minerals?
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Kaolin, Bentonite (Montmorillonite), Magnesium Oxide clay.
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What are the major minerals included in precious gemstones?
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Diamond, Ruby (red Corundum), Sapphire (non-red Corundum), Emerald (Beryl).
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What are the major minerals included in semi-precious gemstones?
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Amethyst (purple Quartz), Citrine (yellow Quartz), Garnet, Jade, Nephrite (Actinolite), Jadeitite (Pyroxene).
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What are the major minerals included in industrial minerals?
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Limestones, Corundum, Staurolite, Garnet, Feldspars/Feldspathoids, Fluorite, Graphite, Gypsum, Mica, Phosphates, Talc, Pyrophyllite, Andalusite, Kyanite.
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Why are minerals in some crystal systems isotropic?
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Isotropic minerals are those minerals that stay extinct under polarized light because the velocity of light is the same in all directions.
I.e. Isometric |
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Why are minerals in some crystal systems unaxial anisotropic or biaxial anisotropic?
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Anisotropic minerals have optic axes are do not stay extinct all the time under polarized light. The index of refraction and velocity of light varies with direction through the crystal lattice. This depends on electron cloud density and retardation of fast and slow rays. The mineral will go extinct along the optical axes.
I.e. Tetragonal, hexagonal, orthorhombic, monoclinic, triclinic. |
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What is the electromagnetic spectrum?
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The entire range of radiant energies or wave frequencies from the longest to the shortest wavelengths.
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List the range of the electromagnetic spectrum.
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Radio waves ↔ Infrared ↔ Visible Light ↔ Ultraviolet ↔ Gamma Rays ↔ Cosmic Rays
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What part of the electromagnetic spectrum is useful in the study of minerals in thin section?
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Visible light
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What is reflection?
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When light is reflected it equals the Angle of Incidence. The amount of light increases with the Angle of Incidence as well.
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What is refraction?
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Light bent when passing from one material to another. There is not refraction if light enters perpendicular to the surface.
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What is the ‘critical’ angle?
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When all light gets reflected, it is at a critical angle which is 90º.
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What is meant by the ‘index of refraction’ for minerals and what factors influence this value in minerals?
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Index of Refraction = n
Snell’s Law = sinθ1 / sinθ2 = n2 / n1 Angle of Incidence = θ1 Angle of Refraction = θ2 When light passes from a lower n to a higher n, light is refracted toward the normal. When light passes from a higher n to a lower n, light is refracted away from the normal. |
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What is the difference between polarized and non-polarized light?
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Polarized light = Light waves which are uniformly aligned in one direction.
Non-polarized light = polarized light in which the electric and magnetic fields vibrate in phase; plane polarized light; what we see. |
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What is the difference between the slow and fast ray?
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A monochromatic ray is split into two rays as it enters the mineral. One ray lags behind the other due to retardation due to differences in velocity. Retardation depends on the thickness of a mineral. The differences of the indices of refraction is called birefringence and we see interference colors in a microscope because of fast and slow ray retardation.
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Why is double refraction easily observed in a calcite rhomb but not a quartz crystal?
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The double refraction in most minerals is so weak that it cannot be observed with the naked eye. However, a small number of minerals have a strong double refraction, which is easily seen when the crystal placed over an image appears to "double" the image.
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What types of minerals exhibit double refraction and why?
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When light rays enter birefringent minerals (minerals with double refraction), the light divides into two rays. The two rays differ in their angle of refraction. Therefore, all birefringent minerals have two refractive indices, one for each ray.
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How do polarizing films polarize light?
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Polarized light waves are light waves in which the vibrations occur in a single plane. When unpolarized light is transmitted through a polarizing film, it emerges with one-half the intensity and with vibrations in a single plane; it emerges as polarized light. As unpolarized light strikes the film, the portion of the waves vibrating in the vertical direction are absorbed by the film. The general rule is that the electromagnetic vibrations which are in a direction parallel to the alignment of the molecules are absorbed.
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What are interference colors and how do they form?
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Interference colors are formed due to retardation of fast and slow rays. Their velocities are different and so when we insert an accessory plate into the microscope we can see how far each ray is retarded by the different colors that appear.
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What is the “optical indicatrix”?
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An optical indicatrix is a 3-dimensional geometric figure on which the index of refraction for the mineral and the vibration direction for light traveling through the mineral are related.
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What controls the shape of an optical indicatrix for a uniaxial mineral?
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A uniaxial mineral has spherical shape because all n values are the same in every direction. We are looking down the c-axis and this is the optic axis for uniaxial minerals.
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What controls the shape of an optical indicatrix for a biaxial mineral?
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A biaxial mineral has an ellipsoid shape because all n values are not equal. The optic axis of a biaxial mineral is when a = c, and b = c. There are two “cuts” where this happens, meaning two optic axes.
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What is the difference between a uniaxial positive and uniaxial negative mineral?
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In uniaxial positive minerals, the ordinary ray (ω) is the fast ray and the extraordinary ray (ε) is the slow ray.
In uniaxial negative minerals, the extraordinary ray (ε) is the fast ray and the ordinary ray (ω) is the slow ray. |
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What is the difference between a biaxial positive and biaxial negative mineral?
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In a biaxial positive mineral, the optic plane is parallel to the slow ray and will see a decrease in colors inside of the isogyres.
In a biaxial negative mineral, the optic plane is parallel to the fast ray and will see an increase in colors inside of the isogyres. |
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What is mineral ‘extinction’ and why does it occur?
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Extinction occurs when one vibration direction of a mineral is parallel with the lower polarizer. As a result no component of the incident light can be resolved into the vibration direction of the upper polarizer, so all the light which passes through the mineral is absorbed at the upper polarizer, and the mineral is black.
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What is the difference between parallel and inclined extinction?
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Parallel Extinction = The mineral grain is extinct when the cleavage or length is aligned with one of the crosshairs.
Inclined Extinction = The mineral is extinct when the cleavage is at an angle to the crosshairs. |
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What is undulatory extinction?
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When parts of the mineral go extinct and not others.
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What is pleochroism?
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The effect present in a mineral exhibiting two or more separate colors when viewed at different angles.
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Identify the 10 minerals of Mohs hardness scale and define their hardness values.
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Talc, Gypsum, Calcite, Fluorite, Apatite, Orthoclase, Quartz, Topaz, Corundum, Diamond
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Identify the 8 minerals of Bowen’s Reaction Series.
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Olivine, Pyroxene, Amphibole, Biotite, Orthoclase, Muscovite, Quartz.
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What is the phrase to remember Moh's Hardness Scale?
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"Two Gypsies Can Forget All Other Quests To Cut Diamonds"
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What is the phrase to remember Bowen's Reaction Series?
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"Old Pirates Always Bellow Out Mean Questions"
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Identify the important igneous, sedimentary, and metamorphic rock forming minerals.
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Sedimentary: Quartz, Feldspars, Biotite, Muscovite, Calcite, Dolomite, Gypsum, Halite
Metamorphic: Quartz, Feldspars, Calcite, Dolomite, Chlorite, Biotite, Garnet, Staurolite, Kyanite, Sillimanite, Talc, Epidote, Glaucophane |
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Identify the important ore minerals.
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Iron: Hematite, Magnetite
Lead: Galena Sulfur: Pyrite Titanium: Rutile Zinc: Sphalerite |
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What controls the shape of an optical indicatrix for a uniaxial mineral?
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A uniaxial mineral has spherical shape because all n values are the same in every direction. We are looking down the c-axis and this is the optic axis for uniaxial minerals.
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What controls the shape of an optical indicatrix for a biaxial mineral?
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A biaxial mineral has an ellipsoid shape because all n values are not equal. The optic axis of a biaxial mineral is when a = c, and b = c. There are two “cuts” where this happens, meaning two optic axes.
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What is the difference between a uniaxial positive and uniaxial negative mineral?
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In uniaxial positive minerals, the ordinary ray (ω) is the fast ray and the extraordinary ray (ε) is the slow ray.
In uniaxial negative minerals, the extraordinary ray (ε) is the fast ray and the ordinary ray (ω) is the slow ray. |
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What is the difference between a biaxial positive and biaxial negative mineral?
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In a biaxial positive mineral, the optic plane is parallel to the slow ray and will see a decrease in colors inside of the isogyres.
In a biaxial negative mineral, the optic plane is parallel to the fast ray and will see an increase in colors inside of the isogyres. |
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What is mineral ‘extinction’ and why does it occur?
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Extinction occurs when one vibration direction of a mineral is parallel with the lower polarizer. As a result no component of the incident light can be resolved into the vibration direction of the upper polarizer, so all the light which passes through the mineral is absorbed at the upper polarizer, and the mineral is black.
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