A Girl and Her Pet Rock (1)

One of the cool things we’re doing for this field class is cutting a thin section of a rock that we picked up on one of the field trips. Chuck, our teacher, has been calling these rocks our “pet rocks.”

I picked my pet rock up at the Green Mountain Kimberlite. And named it Bobby. Yesterday it was time to cut Bobby up to start the creation of the thin section. This involved going to the rock lab in the basement of the geology building, which is an interesting place filled with all sort of intimidating power tools. Some of the saws would probably be more at home in horror movies.

Actually, I started out with three chunks of kimberlite, then showed the benevolent dictator of the rock lab, Paul, all three. Since I’ve never cut a thin section before, I had no idea which would be best. He immediately picked the smallest of the samples, which was also the “chunkiest” since it would be easiest to cut.

I put on a plastic apron (flecked with rock dust rather than the horror movie alternative, thankfully) and some extremely silly looking protective glasses that fit over my own. Paul turned on the saw, which was very, very scary looking. It was a water-cooled affair, so there was a constant drip of water on to the blade. He explained that it was a diamond-bladed saw, though different from the ones most people are used to. The strangest part is that it’s actually very difficult to cut yourself with this particular saw. Paul even touched the blade a couple times while it was running, just to show this. At least as far as flesh goes, it’s yielding enough that your skin and wobbly bits will just flex out of the way of the blade. So if you want to cut yourself, you really have to jam your finger on to it. Or apparently come at it fingernail first, because the saw will just rip through anything solid like tissue paper.

I was very glad I’d recently trimmed my fingernails.

I was pretty intimidated by the saw at first, but it helped that one of my classmates went before me so I could see how he was doing things. I’m not a big fan of power tools, and I’m not a hands-on kind of person.*** My version of being handy is, when forced by circumstance, fishing out the little tool kit my dad gave me and picking up a screw driver. This only happens when my fingernail, my scissors, and my fiance’s pocket knife have all failed to defeat a screw. The only power tool I’ve ever used is a screwdriver. I’ve seen UHF way too many times to be comfortable around saws.

But anyway, once I worked myself up to actually using the saw, it went really well. I sliced Bobby in half length-wise, then trimmed the half the stayed intact down to the right size to fit on a slide. The other half (the thinner half, I think) broke apart as I was running the rock through the saw. I even kept the cut pretty even.

Though of course, a circular saw is not nearly a delicate enough tool to make the sort of even cut necessary for a thin section. When all is said and done, the thin section is going to be so thin that light shows through it. The sort of thin that you measure with microns. (Like your average runway model.) So once the gross cutting was done with the saw, I powered it down and then basically sanded the surface completely flat. You use two different grades of grit on a glass plate, coarse then fine, and basically just sand the thing down until it’s absolutely flat and smooth.

It’s funny, but Paul spent a lot of time telling me and my classmate to not “pet” the smooth surface when rinsing the grit off. And as laughable as that is, it’s hard to do. When something’s that smooth and polished, your fingers just itch to touch it. It’s bad to do so, though, since oils from your hands interfere with the epoxy that gets used later.

So that was the first step. On Monday, step two!

*** Unless you count the time in Fire Academy, but I’d still say there’s a big difference between cutting a car apart with hydraulic sheers and getting your fingers anywhere remotely close to a spinning saw blade.

Leave a Reply

%d bloggers like this: