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Geology 101 Name: Homework assignment 2 Due in class on by e-­‐mail Monday, October 14, 5 p.m. 1. Fidalgo Island, to the north of Seattle, contains an ophiolite (sometimes called an ophiolite sequence). What does the presence of ophiolites on Fidalgo Island suggest about its tectonic past? 2. What property of metal ore deposits makes them likely to be found at convergent boundaries? 3. Ice is, of course, the solid crystalline form of water. Under the definition of “mineral” given in chapter 3, would ice be considered a mineral? Do a little searching on the Web; is there a consensus among various geology sites about whether ice is a mineral or not? 4. Is quartz a mineral or a rock or both? Explain your choice, using the definitions of mineral and rock. 5. Is the mineral property “hardness” defined by how strong the mineral is? To put it another way, if you smash a diamond (Mohs scale hardness 10) with a hammer, are you demonstrating the diamond’s hardness or some other property of the diamond? If the latter, what property or properties will you demonstrate? 6. In an ophiolite, ultramafic rocks are found at the base of the sequence and basalt is found at the top of the sequence, with gabbro found about midway. Explain how this distribution of rocks in an ophiolite is consistent with the composition and texture expected at different levels of the oceanic crust and upper mantle.