This was found in Hout Bay in Cape Town 1989 by my son. it is heavy and appears to be almost solid iron sort of rock. Many years ago I took it to the planetarium in Johannesburg, and they said it could be a metorite. I would like to have some others opinion on this rock that I have kept safe over these years.weight of the stone is 550grams. and there are no sharpe edges on it.
It would be useful to know its density (can compare it with the list of densities in the middle link below).
Calculate its volume by immersion in water. For instance:
1. put one container in another one, fill the middle one with water (carefully, to the brim)
2. carefully (perhaps using a cradle made of thin wire or string) put the specimen in the middle one (overflow goes into outer container)
3. remove middle container without spillage
4. measure volume of water in outer container.
Then density (g/ml) = mass (g) / volume (ml). [ml = cubic cm]
That will give a figure that is good enough for our purposes, though it does not take account of factors such as absorbency of the specimen.
Then have a look at these:
- how to identify a meteorite - http://epswww.unm.edu/iom/ident/index.html
Thank you for getting back to me so soon.
Right, I filled a 500gram container with water, and then placed it into an empty container, did not spill any water, I then placed the rock very carefully into the water. The over flow of water was 90ml.
Mike the container I used was an empty margarine container, which I first put into the empty container, and then filled the inner container, then I very gently placed the rock into it. And as I said the over flow was 90ml measured in a measuring cup..
Hope this makes sense to you.
I don't know how to convert this to density =mass or Volume=cubic cm
Maybe you can figure it out for me.
The rock did not absorb any water.
550g/90ml = 6.1g/ml
That makes it lighter than average for an iron meteorite (8g/ml in the table I referred to), but more dense than iron ore (haematite, 5.1g/ml).
So I suspect it is largely iron, but with impurities (metallic or non-metallic).
It could be man-made or it could be a meteorite
That's a start. See how you get on with the other links.
Mike I got my friend to remeasure it, as I told you I am not perfect, getting a bit long in the tooth for these things
He used the same 500gram container and the over flow he measured was 170 ml measured in a measuring cup.
dont know if this changes any thing??
Yes, that changes things. The density is now 3.2g/ml. Bearing in mind the dark colour and massive appearance, that suggests basalt or perhaps a fine-grained dolerite (both volcanic rocks).
However, that does not fit with the geology of Hout Bay (http://web.uct.ac.za/depts/geolsci/cape.htm).
Please go ahead and do the other tests, eg with a magnet.
Have tested it with 3 different magnets, but it is not magnetic. There are no other bits of rock stuck into it. As you can see by the photo, it is round and fits into the palm of my hand. Wish I was in England so that I could show you it. but Cape Town is a long way away from you. I have written to the Stellenbosh University, and will wait and see if I receive an answer from them, there they can feel it and see it. What else must I do to test this lovely rock.
Re: 'What else must I do to test this lovely rock?'
Follow the guidance in the links in my first reply.
We're looking for a 'body of evidence' ID. That is, there are many things that can be checked, and the more 'meteorite' boxes that are ticked, the greater the liklihood that it really is a meteorite; and the more non-meteorite boxes, the lesser the liklihood of it being a meteorite.
Fusion crust, regmaglypts, iron-nickel metal and magnetism (OK, you've confirmed neither of those apply), density (3.1 is on the light side for a stony meteorite, but yours is only an estimate of its true density), chondrules (you'd probably have to break or saw off a corner to look for these), streak. ...All as in that web page. No point in me copying it here.
Keep in mind the general alternatives: If not a meteorite, your specimen would probably be a natural stone (such as basalt) or a man-made object (such as smelting waste). And in a beach environment, you could find either, since cargo/ballast from wrecked ships can end up there, and rocks and rock-like materials can be added by man to beaches to help control coastal erosion.
Stellenbosh will look at your specimen the same way, and may ask you if they can cut it to look for internal structure (chondrules, eg.) They may also want to make a thin section so they can observe its minerals under the microscope.
You could also try contacting Jeff Kuyken, the author of the last link (http://www.meteorites.com.au/found.html); read the last paragraph on that page.
I wish there was an easier way for you to get the answer.