Instructions for this exercise
The goal of this lab is to emphasize mineral identification by comparing similar minerals. You will be scored on your preparation for lab and participation during lab, but there will be nothing you have to turn in.
- You will be responsible for 3-4 minerals from the set we have examined. For each mineral you should:
- find those others we have studied that might potentially be confused with yours. Be judicious here - quartz will never be confused with galena, for example. You should be able to select no more than 4-5 similar minerals.
- For each of the similar minerals, you should determine a test that can be made in lab to distinguish between the main mineral and that similar mineral, using the techniques you have learned, or you should determine that they are indistinguishable with the techniques you know.
- So, if you have 3 main minerals in the list below, you should end up with perhaps 12 pairs of minerals and 12 ways to distinguish between them.
- Note: I do not want to hear lists of features that differ. I want you to think about what is the best way to tell between the two minerals. For example: Quartz vs. gypsum:
- Do not say this: Quartz has hardness of 7, conchoidal fracture, Specific Gravity of 2.65, while gypsum has hardness of 2, one perfect cleavage, and specific gravity of 2.32. I want you to think, not just copy out of the text.
- You could say cleavage, but what if the samples are fine-grained?
- You could say hardness (and if you did, you should not say Gypsum = 2 and Quartz = 7, you should say that you can scratch gypsum with your fingernail) but this requires you to do something
- The best feature for our purposes is heft: gypsum is significantly lighter than quartz.
We will present these distinguishing characteristics in lab, and after lab, in order that everyone will have these techniques for reference, you should email your results to the list (geo306@lists.wwu.edu).