4200M2K_F11 - GLY4200C Name 90 points October 26, 2011 16...

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1 GLY4200C Name 90 points October 26, 2011 16 took exam - Numbers to the left of the question number in red are the number of incorrect responses. Instructor comments are in blue . Florida Atlantic University MINERALOGY -- MIDTERM 2 EXAMINATION KEY True-False - Print the letter T or F in the blank to indicate if each of the following statements is true or false. Illegible answers are wrong. (1 point each) 0 T 1. All mathematical groups, including crystallographic point and space groups, must contain an identity operation. 2 F 2. All pyramidal forms are closed. 11 F 3. As nuclei grow, their surface area/volume ratio increases. 1 F 4. Growth twins are always penetration twins. 2 T 5. Low-spin Fe 3+ is smaller than high-spin Fe 3+ . 0 T 6.As pressure increases, minerals transform to denser structures, with atoms packed more closely together 1 T 7. Although silicon normally has CN = IV, in the lower mantle the pressures are so great that the CN of silicon is VI. 2 F 8. If two ions have the same charge, the larger ion will enter a crystal structure preferentially. 2 T 9. Crystal classes are defined by the thirty-two possible point groups. 11 F 10. Possible symmetry operations include rotation axes, mirror planes, and an inversion center. What is wrong with this statement? 0 T 11. Faces composed of all anions or all cations are very high energy. They attract ions of opposite sign, grow rapidly, and may grow themselves out of existence. 1 T 12. The calculation of the zone axis is done using the same method as a vector cross- product.
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2 7 F 13. When crystal field splitting occurs, the average of the energy levels of the split d orbital levels moves up or down depending on the electronic environment of the ion in question. 0 T 14. Magnetic separation based on the differing magnetic susceptibilities of different minerals is used in processing minerals since many minerals, especially those containing iron, are attracted to or repelled from a magnet in a strong magnetic field. Magnetic separation is used in both laboratory and commercial scales for mineral separation. 4 T 15. Above the Curie temperature ferromagnetic materials become paramagnetic. 10 F 16. Three d electrons give a large orbital contribution to the magnetic moment of minerals they are in. Spin, not orbital 0 T 17. Many valuable ore minerals have metallic abundances in the trace element range. 3 T 18. The blue color in minerals such as kyanite, glaucophane, crocidolite, and sapphire is the result of a ferric to ferrous charge transfer. 0 T 19. In transition metal minerals, spin contribution to magnetic moments is proportional to the number of unpaired d electrons. 1 F 20. A pinacoid is a closed form consisting of two parallel faces. 2
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This note was uploaded on 12/12/2011 for the course GLY 4200c taught by Professor Warburton during the Fall '10 term at FAU.

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4200M2K_F11 - GLY4200C Name 90 points October 26, 2011 16...

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