We were out walking and we both noticed a round granite rock. It’s very unusual to find a round granite rock that is also rough and grooved on the surface. Glaciers can move and grind rocks but normally the result is smooth since glaciers act like natural rock polishers. Rocks smoothed by water tend to be more flat and oval. When we get home we washed the rock off and I noticed some black markings on one side in the grooved area. I tried washing the black off with a toothbrush but it would not come off. The rock is full of little flecks of white, we presume silica and some red/gold flecks which look to be iron. As we examined it, we both began to think the same thing. Maybe this is not an ordinary rock. Maybe it’s a meteorite. With that thought in mind we went on line to try to find something that would let us identify it.
Dick used the water displacement method to figure out the density. Iron meteorites are normally much heavier than earth rocks like granite. Our rock’s density is a bit on the light side but in the normal range for granite. Meteorites usually have a lot of iron and are often able to attract a magnet. Our rock is very mildly magnetic. It pulls a compass needle toward it. The magnets we have are not strong and they don’t “stick” but you can feel there is a pull between the rock and a magnet. Of course there are earth rocks that do that too.
There are natural rock meteorites, left over from when a planet crashed in Earth and the result turned the Earth molten and created the moon. That type has lower density compared to iron meteorites. There are also stony meteorites called carbonaceous chondrites. These have carbon-bearing matter: elemental carbon, nano diamonds, abiotic organic compounds, fullerenes, and other rare, carbon forms. Carbon-bearing matter from meteorites are thought to be the very beginning of the tree of life. So perhaps what we found is a carbonaceous chrondite. Our rock is 2.4 grams per centimetre cubed or about the range of both carbonaceous chondrites meteorites or common earth rocks like granite.
We dragged out the stereo microscope to have a really close look at the surface. There are some perfectly round tiny nodules visible under a magnifying glass that are tinted green. There are multiple very small perfect half cups of both the white and greenish material as if nodules melted open. Embedded in the rusty coloured material are tiny perfect spheres of black. There are many small, bright metallic flakes over the entire surface. Our rock also does not have the typical exterior melted on look of a meteorite. Still there is that black smudge on one side where the surface has some shallow grooves. Under the microscope it looks like black melted rock material but only deep in the grooves so maybe it is a worn meteorite. On the other hand, you can find black with nodules like that from volcano rocks that formed deep in the earth. Maybe it’s just an interesting earth rock.
So what is it? We are asking some of our friends in the astronomy field. We could spend some money and send it off to be sampled by professionals. I’m not sure I want to hear them say, nope, just an earth rock. It’s more fun to hold it in our hands and think, of such stuff was life likely started in our planet. We shall see. Meantime we had a nice distraction from our day to day cares in the form of a round rock on our path on a country road. We used that to learn a lot about meteorites. We had fun dragging out the old stereo microscope we haven’t used in years. Even if it turns out our rock is just a funny round earth rock, we are glad we found it.
For you, O LORD, have made me glad by your work; at the works of your hands I sing for joy. Psalm 92:4
Blessed are you Lord our God, King of the Universe, who makes the works of creation.