Have we any geologists here? Now with photos.

[MikeG.]

Does anyone here have an interest in, or connection with, geology?

I found a rock in a field near here a couple of days ago that is quite clearly not from round these parts...........my first reaction is that it is a meteorite, being black, and very glassy in parts, as well as pock-marked. It has clearly melted and then hardened. I'll grab a photo in the next few days if anyone is interested, but how do I set about identifying this strange thing?

Mike

 

[Ironballs]

You weren't digging round a slag heap were you Mike

You are in Essex after all....

Already got my coat

 

[Night Train]

If it is glassy then it could be volcanic glass. Meteorites are often iron and nickel as some of the other elements get burnt off on entry though some rocky ones do land.

have a look at this Natural History Museum site for more info.

 

[aldel]

Hi Mike.

Sounds like a lump of slag. Can be a number of reasons. Old iron smelting site produced masses of it generally mineralized. Lime kilns popular in the 1700- 1800's left lots of more glassy slag a little like obsidian. The burnt limestone was used as a 'fertilizer'. It actually improved the Ph levels so grass grew better.

Farmers sometimes spread crushed mill slag on the fields again to replace certain mineral levels and trace elements. Those bags of slag sometimes have lumps in them.

Aldel, (qualified in geology and minerology many years ago)

 

[Grinding One]

If it is magnetic it could be a Meteorite...I use my detector and if I get a large hit it is usually a hot rock,or meteorite.They are quite valuable.

 

[MikeG.]

Thanks guys........

...........sounds interesting enough to grab a photo this evening. If it were meterorite, being the size it is there would be an impact crater half a mile across!!

I'm interested in the slag idea, Aldel. But surely the slag-crushing process wouldn't have left pieces not far off the size of a box file? What historical period are we talking about for the spreading of slag on fields?

Mike

 

[Racers]

Hi,

Power station slag was used alot under paths it some times is a greeny colour and glass like, but I haven't seen big bits.

Pete

 

[Night Train]

Does anyone here have an interest in, or connection with, geology?

I found a rock in a field near here a couple of days ago that is quite clearly not from round these parts...........
Mike

Did you look under the rock to see if there was a tin box containing a note and some money from Tim Robbins to Morgan Freeman?

 

[ste_5150]

Does anyone here have an interest in, or connection with, geology?

I found a rock in a field near here a couple of days ago that is quite clearly not from round these parts...........
Mike

Did you look under the rock to see if there was a tin box containing a note and some money from Tim Robbins to Morgan Freeman?

Ha! you read my mind!

 

[MikeG.]

Possibly the best film ever made.....

 

[Ironballs]

I'd thought the same thing too :lol:

 

[MikeG.]

Here are a couple of piccies:

It is slightly magnetic in parts.........which lends credence to the theory that it is slag. It certainly appears to be a mixture of minerals. You can see the rust patches. The glassy stuff doesn't show up well in these photos, but it is quite striking in reality.

Mike

 

[dickm]

Definitely slag in my book.
But for an authoritative view, you could contact British Geological Survey (somewhere in Leicestershire, I think, but they've definitely got a website), a local Natural History society (who'd probably have a geologist among their number) or a convenient University.
As someone said, a meteorite that size would have caused one h*** of a bang

 

[Drea]

I'm pretty sure it's not a meteorite Mike.

A quick back of the envelope suggests that if it was a meteorite, it would have had energy similar to about 5 tons of TNT when it hit. :shock:

That'll leave a pretty big hole and probably not much meteorite left.

Cheers,

Drea

 

[newt]

Would it not be spherical if a meteorite

 

[MikeG.]

Thanks for that guys.

Now I have to work out how a large chunk of slag ends up in a field in rural East Anglia, miles from any power station or industry. There is a traditional hand-made brick company about 5 miles away, and I have no doubt that there were blacksmith forges and lime kilns dotted around the area.........but even so, this is on a field edge miles from anywhere. Interesting!!

BTW, Drea, I'd be really interested to know the maths behind your calculation.

Mike

 

[Steve Maskery]

BTW, Drea, I'd be really interested to know the maths behind your calculation.

Me too. How do you go about calculating something like that?

Cheers
Steve

 

[Dave S]

BTW, Drea, I'd be really interested to know the maths behind your calculation.

Mike

Probably using the formula for kinetic energy: 0.5 * m * v * v

where m = mass of the 'metorite' in Kg and v = the velocity of the 'meteorite' in m/s.

Dave

 

[Grinding One]

Not all meteroites are round,and they all do not burn up before hitting the Earth,we have a big hole out West that was made by a Meteroite.
They come in all shapes and sizes,not all are heavy either...Remember they are made up with the same things the Earth is made from....Broken bits of blown up stars...I just said some are magnetic and my machine will pick them up in all metal mode.
Found in a field? Well the tractors plow the field and drag the soil around ,could have been moved a few times...farmers around here pick rocks and drop them around the outside of the field so not to hit them at harvest time...

 

[Drea]

BTW, Drea, I'd be really interested to know the maths behind your calculation.

Mike

Probably using the formula for kinetic energy: 0.5 * m * v * v

where m = mass of the 'metorite' in Kg and v = the velocity of the 'meteorite' in m/s.

Dave

Exactly. There's a few assumptions, but it'll not be far from the truth.

Assumptions:
Sphere, 12” diameter
Density of iron meteorite: 8g/cm^3
Velocity of meteorites: 20,000m/s

So, the mass of the thing is volume*density. Volume of a sphere is 4*pi*radius^3 / 3 = 940in^3 or 14827cm^3. So mass is 14827 * 8 = 118616g = 118.6Kg

The kinetic energy of an object is half mass times velocity squared so E = 118.6/2 * 20000^2 = 23720000000 joules = 23.72Gj

One ton of TNT contains 4.184Gj of energy so 23.72/4.184 = 5.66 tons of TNT

Cheers,

Drea