Geology 2311: Take home mineralogy examGeology 2311: Take home mineralogy examOctober 24, 2001Due: Tuesday October 30: leave it in my mail box in the geology office. The resources that you can use toanswer these questions are your text, your cd rom books in HH 120, and your notes. You may also ask me.Each question has equal value. Except for diagrams, please TYPE your answers.1. Pentlandite (page 360 text) is the mineral that we mine for Ni. Please answer the following questions about it:a. Under the topic crystallography, it says that the mineral is isometric and I interpret this to mean maximum symmetry. How do I know that?b. It also says that a=10.07. What does this mean? Explain.c. One of the ways that we can distinguish pentlandite from pyrrhotite is that pentlandite hasa parting on {111}. What is parting? How many directions is that? How do you know?d. The formula for pentlandite is (Fe,Ni)9S8. What does this tell you about its composition? Plot its possible composition (in mole %) on a triangular diagram with Ni, Fe, and S as the corners.e. The text says that Pentlandite commonly occurs as exsolution lamellae within pyrrhotite. What does this mean? What does this tell you about the crystallization history of the pentlandite (and/or pyrrhotite).2. Figure 4.20b in your text shows the phase diagram between albite and silica. a. Redraw this diagram and label all its parts.b. Explain what would happen if I took a melt composed of 80% silica and 20% albite and cooled it from 1800C to 1000C. Use the phase rule in this explanation. (Note that this diagram is slightly more complicated than the one we did in class.)3. It is not unusual to get dispersed elements (ions) in minerals, for example Sr is commonly found inplagioclase.a. In plagioclase, what element is Sr replacing? How do you know? How could you predictthis? Show all your work.b. When I was a graduate student, part of my RA was to do microprobe analysis (I was a trained technician) for others in the department. I had particular problems in analyzing some orthoclase for one fellow graduate student. My totals came to about 96 wt% which was too low. After reanalyzing these samples many times, I decided to do an energy scanto see if there were any elements in the mineral for which I wasn’t analyzing (I routinely analyzed for Ca, Mg, Al, Fe, Si, Ti, K, Na and Mn.) I discovered to my amazement that the mineral contained Ba. When I did a quantitative analysis, I discovered that the mineral contained 4% BaO and my analysis came out to about 100%. During this analysis I also found that I had more Al in the mineral than that predicted in orthoclase. Now my question to you is how is it possible to substitute Ba into orthoclase. Why was there more Al? Which elements do the Ba and Al replace? Could this have been predicted (show your work)? What kind of solid solution is this an example of?4. You are now a new assistant professor of mineralogy in a small regional university. It is not uncommon for the locals to come in with rocks and minerals for you to identify. One day a young woman comes in with a rock with an interesting non metallic blue mineral. You recognize that this is a metamorphic rock but you don’t think that you have ever seen the mineral before, but if you had, it was in a different habit. a. What are the simple tests that you could perform in front of her to narrow down the possibilities.b. After doing these tests, you think you may have a sample that contains sapphire but you are not totally sure. Because this is a valuable mineral, you don’t want to raise thewoman’s hopes. Thus you would like to make some more checks. What could you do next? How could you prove it is sapphire. Tell me in