Naked Science Forum
Non Life Sciences => Geology, Palaeontology & Archaeology => Topic started by: John Chapman on 04/02/2009 00:17:56
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Are there any geologists (or anyone else in Naked Scientist Forum Land) who know where I can get hold of some of the mineral known commonly as olivine. I understand it is the main constituent of peridotite and is a magnesium silicate? Apparently it is the main constituent of the Earth's mantle, so there should be stacks of it about.
There are a couple of us on a different thread
http://www.thenakedscientists.com/forum/index.php?topic=19077.0
who want to have a go at generating heat and sequestering CO2 with it. I could do with about 4 or 5 kilos.
Thanks.
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I dont think youre going to find it in any massive quantities, but if youre wanting to experiment with it, try some online mineral dealers.
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Ultramafic rocks, such as dunite, are very high in olivine. Look for ophiolite sequences, or ultrabasic complexes (containing platinum group elements, nickel and chromite). You will still need some process to separate and concentrate the olivine.
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Bloody Hell Bass!
Ultramafic rocks, such as dunite..... Look for ophiolite sequences, or ultrabasic complexes.....
I have absolutely no experience of geology and I'm afraid that answer was a bit technical for me. I somehow thought that since the mantle is apparently made largely from this material and since, I assume, that the crust on which we live is made from cooled mantle then all I needed was a bucket and spade and the right spot. I sort of hoped that someone would say "you see that mountain? That's olivine"!
I have just looked at a picture of olivine on wikipedia. It's kryptonite! It certainly doesn't look like the commonest mineral on the planet.
But I am beginning to think the experiment I want to do may not necessarily need pure olivine.
Olivine apparently is a magnesium silicate and in nature will combine with CO2 to form magnesium carbonate and silicon dioxide. I am told that following the production of new mountain ranges the level of CO2 in the atmosphere drops significantly. This happens on a geological timescale, of course, but I want to make it happen artificially over several hours by introducing heat. If the dunite you mentioned is a natural good source of olivine (and someone else suggested peridotite) then are these the substances that mountains are made of that absorb CO2? Are there any other minerals which contain high levels of olivine and are any of these easily found by a guy with no geological experience carrying a hammer & bucket?
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Here's the problem- olivine is a very common material in the mantle, but breaks down quickly to form other minerals during geologic processes. So what you need to find is places where mantle rocks are somehow exposed on the surface of the earth.
Mantle material can make it's way to the surface in lava flows- specifically basalt flows. The problem with just collecting bucketfuls of basalt is that you end up with small olivine crystals encased in a glass matrix (when the lava cools quickly at the surface, it doesn't have time to grow mineral crystals, such as olivine).
You could certainly try with basalt, which is relatively plentiful. Besides olivine, basalts will also contain ferro-magnesium silicates (such as pyroxenes and amphiboles) and Ca-rich feldspars (Calcium aluminum silicates).
Places where mantle rocks (also known as ultramafic or ultrabasic rocks) are exposed, are, as one would expect, rare. But they do exist- the most common being "ophiolites", which are sequences of rocks that are thought to represent mantle material deposited at mid-oceanic ridges (or other spreading centers). The island of Cyprus is famous for its ophiolites, as are parts of Turkey and several other places around the world.
So if you really want olivine, it's best to look for ophiolites. Don't know where you live, but give me a location and I'll be happy to see if there are any nearby ophiolites, ultrabasic complexes, or basalts.
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Hi Bass
Thanks for the quick definitions and the whistle-stop tour of geology. I live in the UK.
I don't know if you have looked at the other thread we have on the use of this olivine but basically I'm trying to consider the feasibility of developing a domestic product that will utilise the exothermic reaction that olivine has with CO2 as a source of heat in the home while at the same time sequestering CO2. For this to have any potential it is essential that olivine (or one of the olivine-rich minerals you suggested) be readily and cheaply available. I previously assumed that 'very common' meant 'easily available'. In Wales, where I live, there are lots of old quarries and open cast mines where slate, coal and gravel were once mined. I wondered if, now that these quarries are spent, it would now be possible to start digging again for this most common of minerals which is bound to be just lying around everywhere for the taking! That is until you pointed out it's rarity. Oh dear. All my plans are ruined.
I'm now standing on a chair with a rope around my neck. Before I jump can I just check that the UK isn't the other main site for ophiolites that slipped your mind before? What about dunite and peridotite?
Also you mentioned that basalts contain ferro-magnesium silicates but warned that the olivine is likely to be encapsulated in glass. I'm not sure whether you are saying that basalt may be suitable or not.
I'll just step down off this chair while I wait for a reply.
Thanks for the time you are spending humoring me on this subject.
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Just a stab in the dark, Bass, but couldnt he re-melt basalts and then bring the temperature down slowly until the olivine recrystalizes and then recover the crystals from the melt? Im sure that this is a VERY rigorous process, but according to Bowens reaction series, it should at least be possible (though you would probably use more energy in olivine recovery that you would save in home heating/CO2 sequestration).
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Frethack, that could work, but would be very energy and time (thousands of years) intensive
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Lizard Point in Cornwall has the best exposure of ophiolite in the UK. If you know what you are looking for you can straddle the petrological mohorovich discontinuity ("Moho") which is the change between mantle and crustal rocks.
Unfortunately most of the exposed rock has been weathered into serpentine.
Trodos (sp?) on Cyprus is the best ophiolite in Europe.
Closer to home Anglesey has some blue schist (http://www.kabrna.com/cpgs/anglesey/blueschist.htm) near Llanfair pg and in some cuttings in the A5 (which is far more interesting [;)])
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Hi Mazurka
Anglesea, eh? That's less than an hour from me. What is blue schist? Is it a source of olivine?
Olivine carbonates naturally over geological timescales to produce magnesium carbonate and silicon dioxide and crucially this can be done quickly in the lab using hot CO2. Does blue schist combine with CO2 in nature to produce similar products? Does this sound like the stuff I am looking for?
Thank you for this information. I had almost shelved this idea for the lack of material to experiment with. Have you had a look at the other thread on this subject mentioned in the top post on this thread?
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Hello again Mazurka
I've just had a closer look at the Anglesey webpage you linked to. It describes blue schist as 'blue glaucophanic amphibole'. "Amphibole" was a word used by Bass in an earlier post in which he described it as an example of a ferro-magnesium silicate. That sounds good!!!
Mind you, the Anglesey webpage also says "This site is of international importance so no hammering please!" Bugger!
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Hello, Polish Dance - OH! Mazurka!
Welcome to the forum - and the geology section. The more knowledgeable people we have, the more we might get away from poor answers from Bass and Frethack - both know nothing about real rocks like sandstones and limestones although Frethack was drooling over his carbonate professor last term. (It is about as interested as he gets in real rocks.) Didn't help his grade - still got an "A" - First? in the UK
Frethack, that could work, but would be very energy and time (thousands of years) intensive
Bass, Frethack - On the fifth floor of the Geology Building there at one time was a furnace capable of melting anything and forming rocks for experimental petrology. It doesn't take much time - the whole cycle could be completed in a day or two, depending on how slow of a cooling time one wishes to model.
Gee Bass, I would have thought you would have realized that as you melt those gold ores you process in your basement.
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Bass, Frethack - On the fifth floor of the Geology Building there at one time was a furnace capable of melting anything and forming rocks for experimental petrology. It doesn't take much time - the whole cycle could be completed in a day or two, depending on how slow of a cooling time one wishes to model.
Gee Bass, I would have thought you would have realized that as you melt those gold ores you process in your basement.
And this little furnace can produce 4 to 5 kilos of olivine over a couple of days?
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Yeah, I need to work on those "A's". With grades like that Ill never get into grad school [:(]
btw JimBob...had a pretty cool meeting with my climatology professor. Turns out she isnt the Iron Lady I though she was (no...I dont mean Thatcher-esque). Actually a pretty nice person who is looking for grad students...hehehe. Still not sure I want to be a "foram counter" though (to be read "paleoceanographer").
Anyway, if youd like, I can find out if the furnace is still operational and what its capacity might be.
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Hang on, hang on.
I've completely lost track of this conversation. What are you guys talking about? What does this furnace have to do with olivine? You know I'm in the UK?
For experimentation I am happy to get some material from anywhere. But if I were to design a product suitable for domestic use I need to know that olivine is easily and cheaply available. I heard Chris Smith mention again yesterday on a podcast that olivine is probably the most common mineral on the planet. I thought I'd be tripping over ophiolites, and the like, every time I stepped out my front door!
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It is very common, but unfortunately it is usually locked up with other minerals and will have to be separated. The furnace is used for melting rocks (such as basalts) back into magma, and since olivine is the first mineral (according to Bowens Reaction Series) to begin to crystallize from a melt, it is possible, though probably very costly and VERY time consuming, to extract olivine crystals from slowly recrystallizing molten basalt.
The purpose for checking on the furnace is to get an idea of the time it would take to produce an acceptable quantity of olivine with current technology (well...JimBob went to the college in 1880's so the technology isnt THAT current [;D] )
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frethack is quite right - I was pointing out that a furnace can produce olivine - the Bessamer furnace can produce temperatures up to 2300 °C - that will melt 99.9 % of the rocks in the universe and it is high enough to produce Olivine, which cools out at about 1900 °C.
Re-furbish a steel mill.
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Thanks for that Guys. Very informative.
What about peridotite? Professor Kelleman, who's paper started all this fuss, suggested that carbon sequestration could be effected by pumping hot CO2 directly into beds of peridotite. He suggested actually building heavy industry on top of the beds and just pumping the gas into boreholes. Is this because peridotite contains such a high proportion of olivine that it can be used in it's place without all that furnace fuss?
I still don't understand why, if he could pump CO2 directly into the ground, I can't go along with a spade and bring a bucket full of ground back home. Could peridotite be the answer?
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John
Just say it ain't so...
Chris Smith is probably correct when he says olivine is one of the most abundant minerals on earth- the problem is, almost all of that olivine is in the upper mantle. Peridotite (named after peridot, or olivine) are the rocks of the olivine-rich upper layer of mantle. Peridotite may be abundant in oceanic crust, where they are deposited at mid-oceanic ridges- but are rare on continents. When oceanic crust (peridotite material) gets smashed onto the continents, we call it ophiolite. The peridotites are commonly changed into serpentinites (hydrated Mg/Fe silicates) during this whole smashing process. So even though olivine may be very abundant in the mantle/oceanic crust- it is much more rare and difficult to find walking about on the continents.
I have visited a few exposures of dunite (olivine-rich ultramafic rock) in the North Cascades, Washington, the Stillwater Complex, Montana, and xenoliths (small blobs) in Oregon, California and Arizona. The largest exposure I've seen is at Twin Peaks, near Mt. Baker, in the North Cascades (I was looking at the associated chrome deposits).
Unfortunately, finding abundant olivine in a place you can easily access may prove to be a bit of a challenge.
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Hi Bass, Jimbob, Fretback and Mazurka
All you guys are obviously incredibly knowledgeable about this stuff and you are all saying the same thing. So it seems this may not be the way to save the world. [:(]
So its back to the drawing board!
I want to thank you all for humouring me with this one and for all your detailed explanations.
John
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John - To get some blue schist samples you could try the cuttings along the side of the A5 if you are brave and or daft and don't mind explaining yourself to an inquisitive plod. However, I suspect that the difference in composition / crystal habit of glaucophane (amphibole) as compared to olivine might also make a difference to its affinity for CO2. Sadly for your plan (having read the other thread as well) unaltered olivine is not that easy to come by.
As a slight aside, I was always intrigued by the prospect of using super critical CO2 to carbonate concrete (effectively speeding up the natural re- uptake of CO2 and turning the concrete back into limestone) - which I imagine would have two benefits one of sequestering some of the CO2 released in cement production and secondly making the concrete stronger
@others Experimental petrology? - One word for that - Perverts! [;D]
@ Jim Bob - yes obscure folk dances intrigue me, one day i may even be able to perform one!
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John
Great minds must think alike [;D]
The USGS recently published a US map showing ultramafic rocks to absorb CO2...
http://pubs.usgs.gov/ds/414/
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I have a small piece of olivine in my college bag.. it looks almost like gold ;)
You can buy this mineral in glass industries who produce mineral glasses for watches..
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Bass
That's really interesting. Sorry I didn't thank you earlier. The notifications on this thread seem to have stopped and I thought it had gone cold.
Great. I'm one step closer to conquering the world with this.
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Hi Gigacore
You've gotta tell me where you got it! Where do you keep your college bag at night? Does it have a lock?
Seriously, though, what part of the world are you in and where did you get it?
In the meantime, I'll do a bit of research into the glass industry
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@John Chapman.. lol!
Am in Bangalore, India. I got this mineral from geology department in our college. I will keep this for few more weeks and return as soon as I complete a project on it and few other minerals.
Our college geo department has contact with some mineral glass making industry and they supply such materials to them.. That's how I know where to get this mineral ;)
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Thanks for that Gigacore
You can rest easy tonight. Bangalore is too far for me to come to pinch it.
Thanks for the lead, though. I'll do some research.
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HI gigacore, did you find some olivine? I have some here I found a piece the other day down the Lizard and wondered what it was. I wanted to try experimenting with it to create heat also and was wondering how far you got with this