Mineralogy and Petrology 1Second Hour ExamNovember 15, 2000Name _______________________________Answer question 1. It is worth 20 points. Then answer 3 of questions 2 through 6.. Each of thesequestions is worth 10 points. Spend an average of one minute per point on each question. Please timeyourself.1. The most important group of rock-forming minerals are the silicates. They are classified into 6 groupson the basis of crystal structure. Describe this classification making sure that you use both examplesand diagrams. What are some generalities that can be made about the physical properties of theseclasses. (This question is worth 40% of your grade--make sure you answer it well.)_________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________Answer 3 of questions 2-6.2a. A rock is made up of 100% olivine with a composition of Fo85. How much SiO2 is in the rock? 5 pointsMolecular weights are as follows: SiO2 60.09, MgO=40.32 and FeO=71.85 ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________2b. Define the following terms: (make sure you say how each is formed) 5 points Porphyritic:________________________________________________________________________________________________________________________________________________________________________________________________________________________________Poikilitic: __________________________________________________________________________________________________________________________________________________________________________________________________________________________________________Pegmatitic: