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36 Cards in this Set
- Front
- Back
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What are some types of non-metallic luster?
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Vitreous, pearly, greasy, adamantine, silky, earthy
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What is diaphaneity?
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A minerals ability to transmit light
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What are chromophores?
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Elements that give a mineral its color. Example: Cu, Fe
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What is the difference between idiochromatic minerals and allochromatic minerals?
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Idiochromatic minerals are minerals that have a chromophore as a major component of their chemical structure. Allochromatic minerals have impurities that cause their color. *Structural defects in a mineral can also cause color (Smoky quartz, green diamonds-radiation damage)
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What is a fluorescent mineral?
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A mineral that emits light when exposed to UV radiation. If the emission continues after the energy source is turned off it is phosphorescent, if a mineral emits light when heated it is thermoluminescent.
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Describe "play of colours"
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Play of colours occurs when white light reflected off a mineral is seperated into different wave lengths and scattered in different directions. An example of this is opalescence.
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What is the difference between crystal form, shape, and habit?
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Crystal shape is composed of 2 elements: crystal form (group of crystal faces that are related) and crystal habit (overall shape of a crystal or aggregate of crystals; dependant on the minerals form).
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What is an equant habit? Give an example.
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Same dimensions in all directions. Garnet, spinel.
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What is an acicular habit? Give an example.
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Needle-like. Silimanite
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What is a tabular habit? Give an example.
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Thick sheets, plates. Gypsum, graphite
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What is a colloform habit? Give an example.
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Spherical or hemispherical shapes made of radiating crystals. Hematite
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What are two essential components when it comes to forming a mineral? (think tectonics)
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Time and temperature
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What is a unit cell?
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A unit cell is a tiny box containing one or more atoms that when stacked in 3 dimensions, describe the bulk arrangement of atoms in a crystal
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What is electronegativity?
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The degree to which particular bonds are ionic; describes an atoms ability to attract an atom
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What does the arrangment of atoms in a crystal structure depend upon?
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Ion charge, type of bonding, and ion size
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What is a coordination number?
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The number of atoms/ions that immediately surround an atom/ion
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Which have greater size: cations or anions?
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Anions are bigger because they have more electrons. Size=nucleus + electrons
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When writing the chemical formula for a mineral, which should be listed first in the formula: cations or anions?
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By standard convention, cations should be listed before anions, with the largest cation being listed first. Example: Montmorillonite (Na,Ca)(Al,Mg)2(Si4O10)(OH)2-nH2O
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A mineral has a definite chemical composition. Does this mean that it has a FIXED chemical composition?
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No. Chemical compositional variation within a mineral is referred to as solid solution. This occurs as a result of ions substituting for one another in a crystal structure.
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What are factors that control solid solution?
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Ion size, Ion charges, and temperature/pressure (higher temperature, more substitution).
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What are the three types of solid solution?
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Substitutional, Interstitial, and Omission
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Define simple substitution solid solution.
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Occurs when the charge of the ions is the same and their sizes are nearly equal.
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Define coupled substitution solid solution.
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Occurs if an ion of a different charge is substitued resulting in another substitution to maintain charge balance.
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Define interstitial solid solution.
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Occurs when an ion occupies a normally vacant area of the crystal structure (a void).
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Define Omission solid solution.
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Occurs when an ion of a higher charge substitutes for an ion of lower charge. To maintain charge balance, two of the lower charge ions will be replaced, but the higher charge ion will occupy only one site. The other site becomes vacant.
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What is exosolution?
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Occurs when the conditions change from complete to limited solid solution, and the mineral forms into 2 different phases.
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What is an electron microprobe and what are its 2 fundamental components?
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An instrument for spot chemical analysis of solid state materials at the micron scale. Its 2 fundamental components are the electron optical system and and the x-ray spectrometer.
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What is normalization?
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The process of converting an analysis into a formula.
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Why are electron microprobe analyses useful?
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It detects small compositional variaions within mineral samples, which can help identify minerals that can't be differentiated in hand specimens.
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What is Ostwald ripening?
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Ostwald ripening is the observation that nucleation and precipitation of small particles or crystals gives way to growth of larger particles or crystals over time. Pegmatites!!!
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What are the factors that control crystal growth?
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Temperature, time, abundance of neccesary elements, the presence or absence of a flux
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What is a point defect?
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Where an atom is missing or is in an irregular place in the atomic structure.
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The fundamental building block of the silicates is the silcion-oxygen tetrahedron. What is its forumula?
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SiO4 4-
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What is polymerization?
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The linking of tetrahedra, which results in a wide variety of silicate structures.
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What are the neosilicates/orthosilicates?
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Isolated tetrahedral silicates with indepedant SiO4 structures.
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What are the sorosilicates?
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Paired tetrahedral silicates made up of two tetrahedra that share an oxygen. Formula=Si2O7
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