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Techniques for CollectorsCleaning petrified wood

30th Oct 2016 13:13 UTCJoshua Chambers

Hi all

I found some petrified wood on the beach which comes from a bed containing tons of the stuff. It is banded with pyrite and covered in clay and some algae. I removed most of the clay with a toothbrush and running water, but some is still left. Is there any way I can clean it? The organic removers (bleach, H2O2) that are often used would just dissolve the wood as well, right?

Any ideas?

Thanks

Josh

30th Oct 2016 13:51 UTCBob Harman

Petrified wood is STONE, usually silicified wood, and the use of bleach should be fine for cleaning organics from the crevices. Follow the bleach with a good rinse or a hi pressure cleaning gun. CHEERS.......BOB

30th Oct 2016 14:05 UTCJoshua Chambers

Thanks for the reply Bob.

Good point, completely forgot :-D. The thing is, it's more like coal than petrified wood. I can't find any reference to there being coal at the locality, just petrified wood. It does not feel 'stony' at all, and does crumble very easily. I suppose, as there was a forest, coal is likely to be present. Or perhaps it's wood that hasn't been 'petrified' yet?

(EDIT: after researching, lignite is found at the locality along with the petrified wood. Can you clean lignite?)

Thanks

Josh

30th Oct 2016 14:41 UTCPaul Brandes 🌟 Manager

Joshua,

You may want to provide a photo of the specimen to help us determine the best method of cleaning...

30th Oct 2016 15:41 UTCBob Harman

I agree with PAUL, best send a pix to better evaluate exactly what you have.

To answer your lignite question. Lignite is a rock, sort of an earthy form of coal, somewhere between bituminous coal and (the non-rock) peat. Occasionally fossil remains can be seen in the lignite. I believe lignite would fall apart with a vigorous cleaning so you could not clean it as I mentioned, but lignite is not "petrified wood" as you originally stated so the 2 are way different. In addition, I doubt you would find much lignite on any beach as it would have long ago fallen apart or at least been mined as a "coal" source for heating.

As an aside, many beaches all over the world have very old dead and bleached tree trunks both on the beach surface and below the surface. These are also not petrified wood, but just very old wood. Unusual things can happen as a result of these. Last summer on a Lake Michigan sandy dunes beach in Southern Michigan, a youngster was either injured or killed when he fell into a sink hole while playing on the beach. Subsequent research showed that very long ago that part of the beach had been a woods. Shifting sands covered the wooded areas covering up the tree trunks which had both partially decayed and partially remained intact. Spaces had formed in the areas of the tree trunks and created the sink holes in that area of the dunes on the beach.

Those remaining tree trunks were still very old wood, but not petrified wood or lignite or anything else, just very old partially decayed tree trunks. CHEERS.....BOB

30th Oct 2016 15:49 UTCJoshua Chambers

These pieces must be kept in water otherwise crack and break down from pyrite oxidation. (Discussed here: http://www.mindat.org/mesg-6-386587.html )

(EDIT: As this is lignite, I can keep it out of water right (as opposed to actual petrified wood)? If so, will the pyrite oxidise, how can I stabilise the pyrite?)

Thanks

Josh

30th Oct 2016 15:52 UTCJoshua Chambers

Here is a block from the bed that contains the coal. I broke open the block to reveal lots of coal.

To be fair, this piece I have, wasn't in situ when I found it. It was amongst the greensand (which contains the coal), so it is possible that what I have is an old bit of tree, like Bob suggested. It's just ironic that it was found amongst coal.

Josh

30th Oct 2016 15:54 UTCKeith Wood

I don't want to dispute you, because you were at the site, and collected it, but that doesn't look very woody to me. It looks like coal, or something on the way to becoming coal, that has been sheared in a fault zone. The shearing has mixed clay into it. Would you mind telling us where it came from?

30th Oct 2016 16:00 UTCJoshua Chambers

It came from Compton bay/ Hanover point in the Isle of Wight, England.

http://naturenet.net/blogs/2010/04/11/a-petrifying-walk-on-the-beach/

http://www.discoveringfossils.co.uk/discovering_fossils_hanover_point.pdf

Josh

7th Dec 2016 20:32 UTCTrina Ireland

How rare is green petrified wood? I have seen photos of brown and orange but not many of green with brown in it.

7th Dec 2016 20:53 UTCJoshua Chambers

"Green colored petrified wood is produced by pure reduced iron that is a magnetic, malleable mineral. The chemical composition is Fe. Referred to as native iron, it is quite rare in terrestrial rocks but common in meteorites. Native iron combines with chlorophyll to give tree leaves and plants their green colors but rarely attaches to wood cells"

http://scienceviews.com/parks/woodcolors.html

Just found this, you might find it useful.

Josh

8th Dec 2016 02:14 UTCTrina Ireland

Thanks Josh. I found that information but because I am new to this it is greek to me! The petrified wood is translucent and you cans see dark browns withing the green. The area it was found is in Northwest Idaho but there are big, big chunks of it so I don't understand the "common in meteorites" part. Bare with me...

8th Dec 2016 05:31 UTCDoug Daniels

Not sure about that explanation about iron.... For one, chlorophyll doesn't contain iron (it contains magnesium). And, I don't think you'll find much native iron in petrified wood. However, iron compounds with iron in the +2 valence state tend to be greenish in color (though not always). And, native iron is common in certain classes of meteorites, but not all.

The site about "wood colors" may also have some other errors - such as, purple is caused by manganese. Not necessarily, and likely not at all.

8th Dec 2016 09:28 UTCErik Vercammen Expert

On the captions of green petrified wood from Arizona on Mindat http://www.mindat.org/gallery.php?loctxt=arizona&min=8018 , vanadium is mentioned as the coloring agent. And I can imagine copper minerals giving a green stain on petrified wood.

8th Dec 2016 10:10 UTCAlfredo Petrov Manager

I agree with Doug that that "sciencereviews" "woodcolors" link leads to a rather unreliable package of information, to put it mildly. Green colors might perhaps sometimes be caused by divalent iron, but certainly not uncombined native iron (which is what they're implying by "a magnetic, malleable mineral". (Red, yellow and brown colors in petrified wood on the other hand are usually due to iron.) And some of the other information is spurious too.

Green petrified wood (colored by chromium, I think, but don't quote me on that) is found in Zimbabwe: http://www.mindat.org/photo-717129.html

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