In my thirty years of working seriously with meteorites there is one thing I have not had much experience with, slag. It is listed as one of the more common things submitted to laboratories for examination. I had an interesting and fun time with a piece of slag recently.
I walk and hike most days and have recently increased my steps from 9-10 thousand to 14-15 thousand steps per day. I belong to the local Gem and Mineral society and sometimes hike with a friend from the rock club. He hikes mostly in the desert near town, and I go with him once a week about. He brought me a stone that he found recently. He picked it up far from the things of man, and it really looked like a possible meteorite. The outside looked correct, and the shape was certainly within the range that meteorites have. I was thinking when I saw it that it was one of the few stones that have been handed to me to examine which might be a space rock.
He was ok with me cutting it to see inside. I should say that we did the other home tests. We tested its streak which was brown, not red or black. It was definitely not magnetite or hematite. It was slightly responsive to a magnet. The magnet stuck much better in some spots around the stone than in other areas. I was thinking with that kind of response that there were metal grains. But it was not lumpy and bumpy on the surface so not a chondrite maybe it was an achondrite with metal.
I weighed the stone and marked where 20 gram plus a little would cut off and put the stone in the saw. The endpiece weighed 22 grams perfect for the type specimen. However, upon seeing the inside surfaces I began to worry that it was not a meteorite. There were rather large bubbles inside. Meteorites with just a few exception do not have bubbles. However, a few famous ones do. The other characteristic that I immediately found disturbing was there were no features to be seen on the cut surfaces. It was a uniform brown. No textures of any kind. No minerals at all. I am thinking slag at this point and not meteorites. But it has tiny blebs of metal showing.
As I said at the beginning I have up to this point no experience with slag. I knew of course that it was the result of smelting metal from its ore. It would be reasonable to expect that some of the metal might remain as a small residue in the slag. But I had never done any actual research to find out about slag. The bubbles and the featureless interior were looking bad for it being a meteorite. But the metal blebs very much like those in my impact melt meteorites had me still wanting to investigate the stone a little more.
As we all do today, I went online and inquired if there is residual metal in slag. I got an answer that there is often a small amount of metal remaining in the slag from smelting ore. With that I was nearly convinced that it was a piece of slag. I did not want to give up on my friend just yet and took images of the stone and sent the pictures off to one of the scientists who has done meteorite classifications for me in the past. He concurred that it was likely slag. So that was it. A couple days of high excitement turned to a quick determination that it was manmade waste rock. How it got out in the desert with no industry nearby is a question that remains. But we have often seen manmade things far from where they should be. I have often been reminded as I have traveled the desert how clear it is that others have been everywhere by this time. I was never more aware of that then the time I stood on the very tip top summit of a ridgeline and found a dime lying on the highest rock carefully placed there in the past. So the piece of slag arrived by unknown means out on an alluvial fan in an area that has never had a smelter or iron mine. No industry even similar except a distant blacksmith’s shop might have been in town long ago.
I gave the news to my friend that it was not after all a meteorite but slag. I told him to keep the two pieces none the less as his first meteorwrong that was close in appearance to the real thing. I know that he is likely out there as I write this looking all the time for space rocks. It is my fault too. He and his brother attended my talks on meteorite hunting, Meteor Crater, meteorite identification and immediately bought metal detectors. Their wives kid me that I am responsible for those purchases. They both got different but expensive detectors. Meteorites are rare and hard to just go out and find in the vastness of the desert. But the lure of finding one is very strong in some people. As it is in these two friends of mine. We are going to head out to some dry lake beds near home and see if they can have some luck there with magnet sticks. I feel like I owe them that much after causing them to spend as much as they did on their metal detectors.
I learned a great deal more about slag and meteorites as a result of being handed this rock to look at. I will keep looking too as I hike in the desert close to home. Who knows, it is a big desert and there are meteorites in nearly every square mile. But it takes a lot of walking to stumble upon them. Good thing I am walking more, and I have two eager friends with detectors they are learning to use to help find illusive rocks from space. Maybe I will also know sneaky slag when I see it from now on.
