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Dissolved feldspars or food poisoning?

October 10, 2007

I’ve been out of commission the past 36 hours with one of those quick-onset and intense stomach illnesses. I’m feeling better but it is lingering. It hit me on Monday afternoon while I was point-counting some sandstone thin sections. The culprit may very well be something I ate or some wily virus. But another hypothesis is that my body just simply could not handle the prospect of having to point count multiple samples containing feldspars largely replaced by calcite.


The photo above (from here) shows this nicely. I will be taking photos of my samples soon and will post some of them. They look a lot crappier than this. I think this is what made me violently ill…or maybe it is point-counting in general.


9 Comments leave one →
  1. October 10, 2007 11:45 am

    I have a friend who did a senior thesis that involved point-counting (and more point-counting, and more point-counting) sandstones. She started her talk with a slide that said something like: WARNING! The Surgeon General has determined that point-counting is hazardous to your health.

  2. Karen permalink
    October 10, 2007 6:48 pm

    Heck, I thought I just had a bad cold, but maybe it’s the 60-odd medium sand grain thin sections that I need to point-count. I’m on number 2. And since the source rocks are mostly Franciscan, the sand grains are ALL chlorite-infected. I’ve threatened to lobby to get chlorine removed from the periodic table. This makes one of the members of my thesis committee chuckle, at least.

  3. October 10, 2007 7:11 pm

    Franciscan (shudder)…that stuff is hard enough to understand in place, much less recycled…good luck and feel free to vent your point-counting frustrations here as I will be posting more in coming weeks

  4. October 11, 2007 12:17 am

    You should get a pliant doctor to medically confirm that you are allergic to point counting, then use your ‘disability’ to demand a minion to do it all for you…

  5. October 11, 2007 3:26 am

    As local mineral chemistry nerd, it is my duty to point out that chlorite does not contain any chlorine! It is a sheet silicate- while some of the OH could theoretically be replaced by Cl, in practice this substitution is minor at best.

    And Brian, your point counting is only boring because the replacement carbonate is calcite, and not dolomite. Dolomite makes everything cool.

  6. October 11, 2007 8:34 am

    lab lemming…thanks for keeping us on track

    i wish the point-counting was boring…then it would be easier to decided what kind of feldspar grain it is because there’s more than an outline of a grain with the right cleavage…if only i could see the twinning!

  7. Karen permalink
    October 12, 2007 5:47 pm

    lab lemming,
    I know the chemistry of chlorite, and my advisor knows I know it — that’s why he chuckled. I was being patently silly. In the middle of a semester, you have to be VERY silly to get a rise out of our overworked faculty.

    Thanks for your kind support.

    Point counting is my salvation. I suffer from asthma severe enough to make the usual Master’s thesis effort of geologic mapping somewhat dangerous for me. Looking at sediments from well cores isn’t as sexy, but just as interesting.

    In my sand grains, what isn’t chlorite-infested is iron-stained, so this is a challenging task. Definitely not boring! It’s just that the human body was not designed to spend many continuous hours sitting in one position, staring down a microscope.

  8. October 13, 2007 2:49 pm

    Have you guys considered putting your slides in a probe with a 20×20 autogrid? Getting just the majors shouldn’t take that long…

  9. October 13, 2007 8:13 pm

    lab lemming…while they would likely be an interesting thing to do, at this point i’m way too close to finishing to take on something not in the plans. It’s getting to be that time where I have to squash good ideas in the name of finishing…what a shame!

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