Lab 7 - Lab 6 Miscellaneous volcanic and plutonic SiO2...

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Lab 6 Miscellaneous volcanic and plutonic SiO 2 undersaturated rocks In this lab, you will examine a variety of alkalic and/or SiO 2 undersaturated rocks, such as foid syenites, phonolites, Nephelenites, leucitites, leucitophyres, carbonatites, and kimberlites. Although these samples will seem unrelated, keep in mind that many of these rock types are commonly associated in nature often occurring in the same tectonic setting. 17: Nepheline syenite This is a very leucocratic coarse grained sample. At first sight, the sample may be mistaken for a granite, particularly if you misidentify the sub- to anhedral Ne for Qz! That shouldn’t happen, since Ne is slightly altered, and elongated (sometimes even prismatic). 1- List all minerals occurring in this sample in order of abundance. 2- What is the order of crystallization in this sample? 18: Another Ne syenite The Ne in this sample is a lot easier to identify! Be sure you feel comfortable telling it apart from K-spar. 1- List all minerals occurring in this sample in order of abundance. Indicate which
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Lab 7 - Lab 6 Miscellaneous volcanic and plutonic SiO2...

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