GEOL2500-Final-exam_practice-2020

GEOL 2500 Practice Final Exam Multiple-choice questions (1 point each): 1. Which of the following statements is true? a. the chemical composition of olivine can be described in terms of the relative mole percentages of two end-members, Fe 2 Si 2 O 6 and Mg 2 Si 2 O 6 b. olivine may form in skarns by contact metamorphism c. olivine is one of the most common minerals in the Earth’s transition zone d. olivine is a collective name applied to intermediate members of the solid solution (Mg,Fe) 3 SiO 5 e. olivine is resistant to weathering and accumulates in sand and other clastic sediments 2. Antigorite is a: a. serpentine-group mineral in which TO layers are rolled into tubes 20-30 nm across b. serpentine-group mineral in which TO layers are corrugated due to a slight mismatch between the tetrahedral and octahedral sheets c. dioctahedral phyllosilicate in which TOT layers are corrugated due to a slight mismatch between the tetrahedral and octahedral sheets d. dioctahedral phyllosilicate in which Ca, Na and H 2 O are sandwiched between TOT layers e. serpentine-group mineral in which TOT layers are alternating with interlayer octahedral sheets 3. At room temperature and pressure, the crystal structure of native iron is: a. a body-centered cubic arrangement of Fe atoms b. a cubic close-packed arrangement of Fe atoms, in which octahedral interstitial sites are also occupied by Fe c. a cubic close-packed arrangement of Fe atoms d. a layered arrangement of Fe atoms where successive layers are connected by van der Waals bonds e. a hexagonal close-packed arrangement of Fe atoms 4. Fluorite owes its perfect cleavage on {111} to : a. ionic bonds linking Ca and F atoms in its crystal structure b. van der Waals bonds linking Ca and F atoms in its crystal structure c. ionic bonds linking F atoms in its crystal structure d. hydrogen bonds linking F atoms in its crystal structure e. penetration twinning on {111} 5. The composition shown on the diagram at right (star) corresponds to: a. almandine with 25 mole % pyrope b. pyrope with 5 mole % majorite c. pyrope with 70 mole % almandine d. pyrope with 25 mole % almandine e. a garnet-group mineral with 30 mole % spessartine

GEOL 2500 6. Which of the properties listed below is most useful for the identification of scheelite? a. color b. indentation hardness c. fluorescence d. cleavage e. piezoelectricity 7. The structure of this mineral is an ordered derivative from the crystal structure of calcite: a. magnesite b. dolomite c. siderite d. ilmenite e. rhodochrosite 8. Which of the following minerals is most similar to chalcopyrite in appearance and properties? a. pyrrhotite b. native gold c. pyrite d. arsenopyrite e. native copper 9. Which of the following reactions can explain the formation of talc by hydrolysis? a. CaMg(CO 3 ) 2 + 2SiO 2 ⇔ CaMgSi 2 O 6 + 2CO 2 b. CaMg(CO 3 ) 2 + H 2 O ⇔ Mg(OH) 2 + CaCO 3 + CO 2 c. 2Mg 2 SiO 4 + 3H 2 O ⇔ Mg(OH) 2 + Mg 3 (Si 2 O 5 )(OH) 4 d. (Mg,Fe) 2 SiO 4 + SiO 2 + H 2 O ⇒ Mg 3 Si 4 O 10 (OH) 2 + Fe 2 O 3 e. CaMg(CO 3 ) 2 + 2SiO 2 ⇔ 2C + CaMgSi 2 O 6 + 2O 2 10. Secondary minerals formed by oxidation of pyrite : a. comprise sulfides and arsenides b. have bright blue colors, which can be used in copper exploration c. contain Fe 3 + cations in their crystal structure d. contain ( S 2 ) 2- anions in their crystal structure e. are collectively described as bauxites 11. What is iIllite? a. a trioctahedral expandable clay mineral containing small interlayer cations and H 2 O b. a Mg-Fe phyllosilicate polymorphous with kaolinite c. a sulfate mineral d. a dioctahedral non-expandable clay mineral e. a sulfosalt mineral 12. Which of the following does not apply to cassiterite? a. it commonly forms prismatic crystals and cyclic twins b. it is the major ore mineral for tungsten c. it is commonly found in granites and high-temperature hydrothermal rocks d. it has a tetragonal symmetry e. it may occur as botryoidal aggregates known as “wood tin” 13. From the diagram on the opposite page, choose the crystal habit most typical of galena: a. (1) b. (2) c. (3) d. (4) e. (5)

GEOL 2500 18. Which of the following minerals occurs in nepheline syenites? a. arfvedsonite and richterite b. quartz and corundum c. gibbsite and diaspore d. staurolite and spinel e. epidote and hedenbergite 19. What is the symmetry of almandine? a. 4 b. 422 c. 3m d. 6mm e. 43m 20. Which of the following minerals are most likely to be found in skarns? a. anhydrite, gypsum and halite b. quartz, microcline and muscovite c. diopside, andradite and vesuvianite d. pyrope and omphacite e. quartz, muscovite, topaz and fluorite 21. Which of the following minerals are mined from banded iron formations? a. magnetite and chalcopyrite b. diaspore and böhmite c. pyite and hematite d. magnetite and hematite e. native iron and Fe-Ni alloys 22. Choose the most appropriate formula for the biomineral that makes up the bulk of mol l usc shells: a. MgCO 3 b. Ca 5 (PO 4 ) 3 OH c. CaSO 4 d. CaCO 3 e. Ca 3 (PO 4 ) 2 23. Which of the following minerals commonly show exsolution lamellae ? a. pyrope b. micr ocline c. quartz d. biotite e. gypsum 24. Which of the following consists of numerous , compactly arranged spheres of amorphous silica ~150-300 nm across? a. moonstone b. coesite c. high quartz d. opal e. low quartz

GEOL 2500/2540 25. The diagram at right shows the crystal structure of: a. pyrophyllite b. brucite c. phlogopite d. lizardite e. clinochlore 26. This mineral occurs in evaporites: a. sylvite b. stibnite c. scapolite d. st ishovite e. sanidine 27. Which of the following minerals is most likely to be found in karst caves: a. pyrite b. talc c. marcasite d. c alcite e. a lbit e 28. From the list below, choose one mineral that owes many of its properties to van der Waals forces in its crystal structure: a. halite b. augite c. molybdenite d. muscovite e. galena 29. Plagioclase with 14 mol% anorthite has the following structural formula: a. (Na 0.86 Ca 0.14 )(AlSi 3 O 8 ) b. (Ca 0.86 Na 0.14 )(AlSi 3 O 8 ) c. (Na 0.86 Ca 0.14 )(Al 0.86 Si 3.14 O 8 ) d. (Na 0.86 Ca 0.14 )(Al 1.14 Si 2.86 O 8 ) e. (Ca 0.14 Na 0.86 )(Al 1.86 Si 2.14 O 8 ) 30. Which of the following is inapplicable to tridymite: a. it can be classified as a framework silicate b. it is polymorphous with coesite c. it is stable at higher pressures than low quartz d. it forms platy hexagonal crystals in lavas e. its structure can be described as consisting of interconnected (SiO 4 ) 4- tetrahedra 31. Unlike in diamond, each C atom in the structure of graphite is bonded to: a. three other carbon atoms b. four other carbon atoms c. six other carbon atoms d. two other carbon atoms e. none of the above

GEOL 2500 c. intermediate members of the clinochlore-chamosite series d. intermediate members of the grossular-andradite series e. intermediate members of the hedenbergite-diopside series 39. Which of the following minerals shows strong pleochroism? a. albite b. cordierite c. spinel d. wollastonite e. orthoclase 40. Which of the following minerals has both (SiO 4 ) 4- and (Si 2 O 7 ) 6- groups in its crystal structure? a. epidote b. schorl c. marialite d. spodumene e. lizardite 41. Zeolites : a. are hydrous sheet silicates of K, Na or Ca b. contain Be and B substituting for Si in their crystal structure c. are also known as expandable clays owing to their ability to absorb water d. are used in environmental technologies owing to their ability to convert CO 2 to CH 4 e. contain water in large interconnected cavities in their crystal structure 42. Which of the following minerals can be described as malleable? a. diamond and graphite b. native copper and native gold c. micas and brittle micas d. chlorites e. talc and pyrophyllite 43. In a hexagonal close-packed arrangement of oxygen atoms, all octahedral interstices are occupied by element A. What is the formula of this mineral? a. AO b. AO 4 c. AO 2 d. A 4 O e. A 2 O 44. Which of the following minerals is mined from placers and used as a gemstone? a. sphalerite b. schorl c. marcasite d. corundum e. pyrophyllite 45. Sanidine is: a. a high-temperature plagioclase showing a disordered distribution of Ca and Na b. a high-temperature alkali feldspar showing a disordered distribution of K and Na c. a high-temperature plagioclase showing a disordered distribution of Al and Si d. a high-temperature K feldspar showing a disordered distribution of Al and Si e. a high-temperature alkali feldspar showing a disordered distribution of K and Ca

GEOL 2500 Completion questions (3 points each) 46. Olivine of composition (Fe 1.62 Mg 0.24 Mn 0.12 Ca 0.02 )SiO 4 contains _______ mol.% of the magnesium end-member, called _______________________ and _______ mol.% of Fe 2 SiO 4 . 47. An unknown mineral was analyzed to contain ~80 wt.% Fe and 20% Si; based on this analysis, its formula is __________________. 48. The mineral __________________ is sometimes produced by reaction of sedimentary _________________ rocks with sulfate fluids and may form crystals reaching several meters in length. 49. The reaction written below describes ______________________ of chalcopyrite, which produces goethite and the blue copper mineral called ____________________. 12CuFeS 2 + 8CO 2 + 10H 2 O + 63O 2 ⇒ 4Cu 3 (CO 3 ) 2 (OH) 2 + 12FeOOH + 24(SO 4 ) 2- 50. Amethyst can be distinguished from purple fluorite by its higher _________________, lower density and ____________________ symmetry of its crystals. 51. ____________________ is an amphibole-group mineral found in high-pressure metamorphic rocks from subduction zones, termed ______________________. 52. _____________________ (FeFe 2 O 4 ) has an inverse ____________________ structure. 53. Native sulfur forms by the oxidation of ___________________ around volcanic ____________________. 54. ____________________ is a pyroxene-group mineral from _____________________ that can be used as a Li ore. 55. In the tetrahedral sheet shown below, ¼ of all Si is replaced by Fe 3+ . The formula of this sheet is _____________________.