Meteorite??

[SilentKnight]

One of my relatives recently found a rock and has been trying to figure out what kind of rock it is. The rock is very heavy at 58 lbs., very porous, and not magnetic. The rock is about the size of a football and was found in a riverbed. My relative took it to a chemistry teacher who told him that it contains iridium. The chemistry teacher thinks it might be a meteorite. Lead and iron are NOT present in the rocks composition also.

Any ideas of what it may be??

[EnigmaOne]

It’s my guess that, based on sheer size alone, it probably isn’t a piece of fossilized fish crap.

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–Kalél
TheHungerSite.com
“If ignorance is bliss, you must be orgasmic.”
“Well, there was that thing with the Cheese-Wiz…but I’m feeling much better now!” – John Astin, Night Court

[Padeye]

A 58lb fossilized fish turd? Must be from the extinct Jurassic large ass bass. You get the time machine ready. I’ll stock the cooler with beer and gas the boat.

You said the rock is porous, do you mean like pumice or a metamorphic rock or swiss cheese? It’s heavy but how dense is it?

Iridium, huh. Does it have a melted Motorola logo on it?

[Rhythmdvl]

Hello all. The Museum of Natural History in New York has an excellent exhibit on meteors. (Though I heard they may be losing their most dramatic specimen). In the exhibit is a wonderful display of meteor-wrongs, terrestrial objects once thought to be meteorites. While I can’t quote from the display, here is a bit form a commercial site that should help answer the question. There is a lot more on the page (pictures, etc) so you may want to go there.

Most meteorites contain some iron and tend to be very heavy. Iron meteorites are approximately four times as heavy as a terrestrial rock of the same size; stone meteorites about three times as heavy.

No iron in the sample? Maybe you have a very rare meteorite. However,

There is a laboratory test that will nearly always confirm the identity of a meteorite, and that is the test for nickel. Almost all meteorites contain nickel, but it is very rarely found in terrestrial rocks.

I think if it has neither of these, your friend has either found an incredibly rare meteorite, or a big, heavy paperweight. At the sight there are more physical descriptions of what to look for (with pictures) and a bit more on the composition.

I think that the rock’s location speaks to its possible origin. Factories typically sit alongside riverbeds and dump a host of industrial byproducts into the water. These can travel quite a distance from their source and last for quite some time. Many types of foundries or manufacturing plants produce lumpy, porous rocks (weathered in the water they take on an odd aspect) that defy our common experience.

I hope this helps.

Rhythmdvl
By the way, wouldn’t it be more proper to say I found somemeteorite or just here is a lump of meteorite? To say I found a meteorite is common, but it is like saying I have a quartzite on my desk.

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Once in a while you can get shown the light
in the strangest of places
if you look at it right…

[SilentKnight]

Well, with the evidence you guys provide, I guess it’s not a meteorite.

Thanks, even though it isn’t a meteorite.

[Fillet]

I think Rhythmdvl’s point about odd-looking industrial waste is a good one to consider. I did a rough estimate of the density of your rock (don’t know the exact dimensions of a football for comparison) and got approximately 3.0 to 3.5 g/cm^3, which is actually not unduly heavy for an ordinary rock. (Iron/nickel meteorites, by contrast, are about 5.5 g/cm^3).

Just out of curiosity, how did the chemistry teacher determine that there was iridium in the rock? I’m not certain where your relative picked up the rock, but I would also add that some igneous rocks (particularly basalts) will have a small amount of iridium in them. The big difference between earth rocks and meteorites is that iridium is far more abundant in meteorites.

Rhythmdvl, I guess you could say that while many geological terms that end in -ite refer to a rock or mineral of indefinite quantity, the term meteorite is applied to a specific object. So, it’s okay to say that you found “a” meteorite.

[Rhythmdvl]

Fillet I agree that it is not wrong to say ‘a meteorite’ per se, but am wondering if it would not be more proper (if that makes sense) to drop the ‘a’. When it is up in space, it is A meteor. It does not technically become (a) meteorite until it touches down in Zeak’s back yard. The suffix -ite only gets attached once the lump has made its Earthly debut. The distinction is made because once a part of the Earth, it is considered part of the indefinite supply of rocks Kang and Kodos have hurled at the Earth. Using the term a meteorite to refer to a specific meteor makes sense, but couldn’t you drop it to refer to a fragment of meteorite? Picayune, sure, but in the realm of grammar, I so seldom get a chance to know what I am talking about. Thanks for listening,
Rhythmdvl

Once in a while you can get shown the light
in the strangest of places
if you look at it right…

[SilentKnight]

I don’t know how he or she detected the iridium. I’ve already asked and hopefully I’ll get a response soon over the net.

If it isn’t a meteorite, which I’m pretty convinced it isn’t, what type of rock could it be?
Thanks

[Rhythmdvl]

A couple excerpts"]http://www.shef.ac.uk/chemistry/web-elements/webelements/elements/text/key/Ir.html]excerpts from the University of Sheffield:

The name iridium is appropriate, for its salts are highly coloured. Iridium is white, similar to platinum, but with a slight yellowish cast. It is very hard and brittle, making it very hard to machine, form, or work. It is the most corrosion resistant metal known, and was used in making the standard metre bar of Paris, which is a 90% platinum-10% iridium alloy. This metre bar has since been replaced as a fundamental unit of length (see Krypton).

Is it possible that they think it is iridium based on appearance? On a side note, I wonder what they did with the old bar? Throw it out with the official cherry flavor sample? Sell it? Melt it down? Anyway, that is a brief physical description. A little bit on the chemistry:

Preliminary treatment of the ore or base metal byproduct is required to remove silver, gold, palladium, and platinum. The residue is melted with sodium bisulphate (NaHSO4) and the resulting mixture extracted with water to give a solution containing rhodium sulphate, Rh2(SO4)3. The insoluble residue contains the iridium. The residue is melted with Na2O2 and extracted into water to remove ruthenium and osmium salts. The residue contains iridium oxide, IrO2. Dissolution of the oxide in regia (a mixture of hydrochloric acid, HCl, and nitric acid, HNO3) gives a solution containing pure (NH4)3IrCl6. Evaporation to dryness and burning under hydrogen gas gives pure iridium

Sounds like a bit of effort, but if the chem teacher had a lot of time on his hands, thought he saw iridium, maybe he put in the effort. I assume that finding iridium in the sample helped give rise to the thought that it is a meteor. There is a small but distinct iridium layer at the K/T boundary, a time of mass extinction. The iridium layer is pretty much uniformly found all over the Earth where rock from that time period is exposed. The layer lends support to the theory that there was a massive meteor impact that helped cause the extinction.

As to where it came from, there is also this on the site:

The industrial extraction of iridium is complex as the metal occurs in ores mixed with other metals such as rhodium, palladium, silver, platinum, and gold. Sometimes extraction of the precious metals such as iridium, rhodium, platinum and palladium is the main focus of a partiular industrial operation while in other cases it is a byproduct. The extraction is complex because of the other metals present and only worthwhile since iridium is useful as a specialist metal and is the basis of some catalysts in industry.

Italics are mine. This seems to add a little weight to the guess that it is an industrial byproduct. Most of the rivers in this country have had factories or mills on them at one time or another. Any rock-like effluent from a factory (or its demolition) will last much longer than the factory or its memory. I’d show it to a it to a geologist or an industrial engineer to find out what it is. No offence meant to the chemists out there, of course. Again, thanks for listening.

Rhythmdvl

Once in a while you can get shown the light
in the strangest of places
if you look at it right…

[Fillet]

Rhythmdvl, sorry for taking so long to get back to you.

I haven’t really thought about the grammar of this before. FWIW, I think it’s a matter of whether or not it makes sense to think of the object in question as a representative of one thing or class of things, or rather as one of many types of something. To draw some parallels with other geological terms:

1. A mineral or rock name is usually reserved for a material with specific characteristics. For minerals, those characteristics include chemical formula, crystalline structure, density, hardness, color, luster, cleavage and fracture. For rocks there’s a bit more slop, but they are typically defined by the presence of particular minerals and textures (different criteria exist for igneous, sedimentary and metamorphic rocks). Sometimes these names are also used for a class of similar minerals or rocks as an all-purpose moniker (e.g., mica as a general name for a sheet-like, platy mineral, or sandstone as a general name for all rocks that are composed of siliciclastic grains of a certain size range).

For either of these circumstances we’d refer to the material in question the same way you’d talk about sugar: “some mica,” “some sandstone.”

2. If we wanted to acknowledge that there were different types within a given class, we’d take that all-purpose moniker and make it a plural noun. We could also then discuss a generic example of that plural noun.

Just as a biologist might now talk about various “sugars,” and point to glucose as an example of “a sugar,” geologists can now talk about various “micas” or “sandstones” and point to muscovite and arkose as examples of “a mica” and “a sandstone,” respectively.

So to me, the term meteorite falls under the second example above, because it is an all-purpose moniker that describes a particular class of rocks (those that are extraterrestrial in origin), and because there are several possible types (e.g., carbonaceous chondrite is an example of “a meteorite”).

None of this stops you, of course, from referring to “a fragment of meteorite” or “some meteoritic material.” It would be clear to any geologist exactly what you meant, and I don’t think any would want to argue with you about the grammar. Just because we do something out of custom doesn’t mean it’s linguistically correct.

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SilentKnight, it’s really hard to say what the rock might be without seeing it in person. (Look at how much yakking there was about what kind of rocks the martian Pathfinder was seeing!) If there is any way you can post a picture of it, I’d be willing to hazard a guess. If not, and you’re really itching to know, drop me an email & I’ll give you my address so that you can send me a small piece. Knowing exactly where it was found will also help narrow down the possibilities for a source.

BTW, not to be too alarmist or anything, but if there’s a chance that this IS a piece of industrial slag, you might want to be careful about handling it with your bare hands for too long (at least wash up with lots of soap afterward).