Micrometeorite candidates

The kids and I took apart a defective hard drive yesterday, and I used one of the magnets (in a plastic bag, which I then inverted) to fish for micrometeorites in the soil near a downspout.  I found a few plausible candidates, as well as a bunch of surprisingly pretty microscopic ferrous dust. Here is a particularly pretty area.  The pointer is pointing to a round micrometeorite candidate.  It's stuck to some probably earth-origin stuff--the hard drive magnet magnetized all the samples, so they stick together.  There is also a pretty piece of glass or crystal closer to the top edge.

I ended up preparing a slide with four candidates (one a bit dubious) mounted under a glass coverslip.  It's hard to grab pieces as they are very tiny--though big enough to see naked eye as a tiny dot--and stuck magnetically to other things.  In particular, I lost the round one in the first photo, as it just shot away when I tried to grab it with a toothpick (which looked like a big blunt log under the microscope).  Here's one that didn't get away.  It's about 60% of the size of the ball in the first picture.  You can't tell in the photo, but if you shine the light on this, it's very metallic--a nice silvery object. I ended up perfecting a method for extracting them.  First, I use the toothpick to sweep the area around it clean, looking in the microscope most of the time.  It's confusing, since the miscroscope reverses the view, but eventually the brain gets used to it.  Then I wet the toothpick with acetone.  The micrometeorite candidate sticks to the toothpick.  I then transfer it to a clean piece of glass.  Because the acetone evaporates so quickly, it's easy to just wipe the toothpick on the glass and the micrometeorite drops off.  I lost two promising samples--especially that nice big round one in the first photo--before I got the above two.

From what I've read, rounded things that look like they were partly melted are good candidates.  Here is a less rounded one that ended up on the slide of the four that I saved.  I don't know how it got there, as I only intentionally transferred three to it, if memory saves.  Maybe it accidentally got carried there.  It looks too rough-edged to be a micrometeorite.  However, I've also read that they can avoid atmospheric melting by being small, so maybe rough-edged things count as candidates, too.  It, too, has a nice shine to it, though the photo doesn't show it.

If you try to view these with bright-field microscopy, of course you just get black silhouettes.  What I did is I taped a bright LED flashlight to the microscope, pointing at the sample, and then I took timed exposures, holding the camera to the eyepiece (sometimes with some sort of adapter to keep the camera in place).  For the second two photos, I found a way of adding more light.  I took the microscope outdoors, and then reflected sunlight onto the slide with a mirror (actually, a hard drive platter--they make lovely mirrors). The photos were taken with point and shoot cameras hand-held to microscope eyepieces, with some loose-fitting adapters to make it easier. The first photo was with a Sony P100 through the 10X Huygens eyepiece that the microscope came with. The second and third photos were with a Canon G7 through a Rini 30mm telescope eyepiece, using my home-made telescope-to-microscope eyepiece adapter. Update: I wish I knew how to better identify micrometeorites. The very round one may not be one--see this article.

Hunting for micrometeorites

Inspired by stuff on the web (e.g., here), I went hunting for micrometeorites. I wrapped a magnet with plastic wrap, and ran it through the dirt under one of our house's downspouts. Apparently meteorites have high iron content so magnets capture them. There was some magnetic dust. I then transfered a couple of pieces of it to a microscope slide and had a look. I saw black chunks of stuff with transmitted light, unsurprisingly, but they became pretty and shiny when I shone a flashlight on them. The two largest ones had rough edges. Micrometeorites are supposed to be smoother due to their hot passage through the atmosphere. But moving the slide around, I cam on a smaller piece with smoother edges and interesting texture that matched what one would expect a meteorite to look like. There was some shiny bumpiness, some small pit-like spots and some interesting rod/wave like areas.

I tried to save the tiny piece for future observations. I tried to stick it to some sticky tape, but the goo made it very hard to observe under the microscope. So I ended up dissolving the goo with acetone to recover the piece. As a side-effect, the piece became cleaner and was brightly metallic under the microscope. Unfortunately, I eventually lost it. It was very small, about four or five times longer than wide, and the width was about that of a hair or maybe a touch more. I lost it when I tried to transfer it with the tip of a needle from a dirtier cover glass to a cleaner one, but somehow it just disappeared--I used a powerful loupe to try to find it, but couldn't. Oh well.

At least the kids got to see it. I don't know it was a meteorite, of course. Too bad I lost it before taking a picture.