"Malachite after wood"

Hi all,

I hesitate to post this in the Fakes section because I don't want to imply that the seller is a malicious scam artist!!! More than likely, he/she was just misinformed, or the piece is mislabeled, or what have you.

[cgi.ebay.com]

Or actually it's just as possible that I am wrong! However I have a piece that I think is virtually the same as this one, and I was told that it is indeed petrified wood, just chalcedony replacing old fossilized wood, but colored by chromium - no Cu involved at all.

Are these two really different pieces? I have seen the copper pseudos after wood at the "Petrified Wood Museum" (there's a store right outside of Holbrook, AZ, near the Petrified Forest National Park, a pretty new store that has an absolutely amazing collection of petrified wood! Including some native copper crystallizing on petrified wood, amongst others. I need to go back and get some pictures - really amazing stuff in there!!!) but I am under the impression that those are pretty much unique. I mean, there's very very little copper in that part of Arizona from what I know.

So basically, do Malachite pseudos after wood really exist? Or is it just the "regular" chalcedony colored by Cr? My hunch is that it's a mislabel or perhaps indeed deception - that a lot more people would be impressed by Malachite (a mineral they've actually heard of) instead of just regular petrified wood colored by Cr. I have one and it is in fact very cool, and expensive. This one's about the same size and same price as mine, but mine is a much darker, more saturated green, unless these pictures are way off.

Anyone have any ideas about this auction?

(If the seller reads this, I'm not trying to call anyone out as a scammer! Just trying to get my own facts straight, and I plan on sending the seller a message pointing to this thread so no one else will be misinformed!)

Thanks all

Ben Kirchner

Ben, the seller may well be correct in this case (although I can't make a determination from photos). Various copper minerals replacing wood are not that rare, and certainly a lot more common than chromium-bearing chalcedony replacing wood (which only comes from a single locality in Zimbabwe, as far as I'm aware).

Actually the Cr colored petrified wood tends to be a bit more expensive and rare. If it is malachite might be a bit questionable since it looks a bit too blue on my monitor. Most likely the piece started out as partially chalcocite after wood that has subsequently been oxidized to some combination of secondary copper minerals.

Quote

chromium-bearing chalcedony replacing wood (which only comes from a single locality in Zimbabwe, as far as I'm aware).

There is some from northern Arizona.



Edited 1 time(s). Last edit at 09/29/2009 05:39PM by David Von Bargen.

Hi Ben,

Dana Slaughter, dminerals1963, is a contributor to mindat, a very well respected part-time mineral dealer, and a member of the Arizona Mineral and Mining Museum Foundation. As such, he takes particular pride in the specimens that he does list and sell on ebay, and as you might be able to tell, goes the 'extra mile' to document and describe his items. Those who know him notice his passion for minerals and the correct identification, history, and pedigree that he seeks.

The Arizona Mining and Mineral Museum, located in downtown Phoenix, has a number of interesting copper after, and on, wood replacement specimens, some with minor malachite associations from Arizona localities. One could also ask a number of southern Utah collectors, such as Joe Marty, Brent Thorne, or Pat Haynes, (also mindat contributors), about a number of interesting mineral replacements of wood that they have personally collected.

As for the color of the specimen, the picture on ebay appears slightly more blue than reality. I have no doubt that Dana is correct in what he has listed, and stated in the description.

Phil

Not sure I would say Cu (or Cu minerals) after wood is rare. At the recent Denver show, one dealer had a few dozen specimens, all quite real (at least as far as I could tell).

Hi,

Is that Dana Slaughter?

I didn't even look at the seller name. I am so embarrassed right now. My first piece I bought was from Dana and I'm very aware of how knowledgeable he is, having read many of his posts and seen his other work.

How embarrassing. I owe a major apology!!!

I'm hanging my head in complete shame right now.

About the subject though: Northern AZ does have a small amount of "Green Petrified Wood" (colored by Cr.) I still haven't been to the museum in Phoenix but it is on the list, next time I get a free weekend day. The "museum" in the store outside of Holbrook is fabulous too, especially in this regard, and has some fantastic pieces. I wonder how the AZ pieces compare to those from Zimbabwe?

I'm sending my apology to Dana now. I apologize to everyone else, also, for not doing my research before hand. Anyway, I do respect Dana's auctions and minerals and I agree with you, Phil, I completely respect any of his IDs. At least from my point of view, as I'm not so experienced, his word is pretty much gospel by my standards. Same goes with all of those I consider Arizona experts - there are quite a few. If I'm going to question something any of these experts say, Dana included, I would spend a long long time researching my case before ever saying anything like that. I assumed this was more of a typical ebay retail mineral sale: again, incredibly stupid of me to assume.

Take this as a lesson to do all the research and not make assumptions before correcting someone!!!

In fact, as the highest compliment and apology I can send, I'm going to buy this rock! I always need new funky Arizona pieces, and this one is great. Like I told my girlfriend, if it really was malachite after wood it would be amazing. Since it apparently is, I guess I'll put my money where my mouth is!

Thanks for the corrections and my apologies again.

Ben Kirchner

So really, are copper minerals after wood not that uncommon? Not that they're a dime a dozen, but I figured they were quite rare. Very interesting. The store outside of Holbrook has a phenomenal display: large, (table-top sized) pieces of wood with large sections of crystallized native copper, and many other outstanding pieces. I guess that's why I figured they were rare; although I guess logically, if there's all those great examples in one place, there should be all grades of less spectacular examples out there, and thus not so rare.

Thanks for helping me figure out this thought exercise! Next time I make it to Holbrook (for absolutely no reason other than to go to this shop and maybe the Pet. Forest NP, no offense to Holbrook) I will try to get permission to take pictures and upload them here, because they should be documented. Really amazing. Anyway, the malachite after wood is purchased and on the way!

Anyone have good examples of copper/cu minerals after wood?

Ben Kirchner

Ben, there are famous examples of 2,000 year old native copper after wooden mine beams from Roman mines in Cyprus; 70 year old examples of native copper partially replacing wood from the Ray mine in Arizona; chalcocite and cuprite replacing Miocene age wood from Bolivia; and, if we go away from wood to other organic substrates, atacamite after a mouse, from Russia; at least two human beings (ancient miners) replaced by copper minerals - one from the Atacama desert, now living at the American Museum in NY, and another in Sweden. Which all goes to show that copper minerals can replace oganic matter quite easily, in a wide range of environments. Fascinating.

And let us not forget "Malachite Man"!

[www.talkorigins.org]

When I worked at the Ray Mine in 1995 a shot in the West Pit literally blew timbers loaded with copper replacing wood (as well as the nails) all over the place. In addition, the Nacimiento Mine in northern New Mexico has Chalcocite replacements of wood, which then get a green "malachite-looking" coating on them

I was aware of copper after wood in mines (wood from the mine) and some of those cool copper replacements. I remember a Copper after railroad spike from Bisbee auction that was incredibly cool, and Turquoise fossils. The "Malachite Man" is hilarious! But at the same time, politics aside, also again incredibly cool. I definitely wasn't aware of that!

But I don't think these are the same process at work, are they? For malachite after petrified wood, was it originally wood, then replaced by silica (chalcedony) and then replaced by malachite? My understanding was that pseudomorphs after quartz are incredibly rare. (Which of course wouldn't rule this out, but makes it less likely?) Or did copper carbonate solution replace the original wood, before it was petrified? Huh. Hmm.

Or is it the same process; newer wood (not Triassic as is the petrified wood in this area, Northern AZ for reference) that was replaced during a much more recent process?

I'm way more confused than I started - excellent, I love when minerals do that...

Ben Kirchner

On that piece, I would guess that the original replacements were silica and chalcocite (plus calcite etc). The wood makes an excellent locally reducing environment that will precipitate a lot of things. Later it became an oxidizing environment and the copper sulfides became secondary copper minerals.

> Turquoise fossils

Many of these are not turquoise (are there any that have been categorically proven as turquoise?)

Check out the mindat page on "odontolite".

Jolyon

Ben,

Just thought I would give you a link to an earlier thread where I found Chryscolla "on" wood at one of the oldest copper mines in the country. I had a professional do what Alfredo suggested and Chryscolla was the diagnosis.

[www.mindat.org]



Edited 1 time(s). Last edit at 09/30/2009 01:09PM by David Bernstein.

Thanks guys! Interesting stuff. Jolyon, I saw one of these "Turquoise fossils" on a major-dealer's auction site and just assumed that that's what it was. Interesting! This is basically saying that it's not turquoise but really just colored blue by Mn ions? Wow, that's a pretty big difference. To call something turquoise is one thing if it's chrysocolla or colored blue by copper but if there's no copper present.. You'd think that would be pretty easy to discern.

So are there any real turquoise after fossils? Good question! Like I said, I saw it on a huge dealer's site and assumed it to be true. David Bargen thanks for the idea on this piece. It should be in my hands tomorrow, and maybe I'll be able to get some really good close-up pics.. I'll try.

David and Darren, those are cool stories about mine-wood replacements. I love that stuff.. I would definitely want one, especially from the Ray mine (or any AZ mine) in my collection. Fascinating stuff! Thank you guys!

Ben Kirchner

Many years ago - perhaps 1986 or so - I saw a small log of what was called "malachite petrified wood" at the show in Franklin, NC. It certainly looked like that was what it was. It was beautiful, and very memorable.

I have a piece of a cedar (??) post from a Cypriot mine that has quite a number of very small bits of copper (< 1 mm diam.) included in it.




Alfredo Petrov Wrote:
-------------------------------------------------------
> Ben, there are famous examples of 2,000 year old
> native copper after wooden mine beams from Roman
> mines in Cyprus; 70 year old examples of native
> copper partially replacing wood from the Ray mine
> in Arizona; chalcocite and cuprite replacing
> Miocene age wood from Bolivia; and, if we go away
> from wood to other organic substrates, atacamite
> after a mouse, from Russia; at least two human
> beings (ancient miners) replaced by copper
> minerals - one from the Atacama desert, now living
> at the American Museum in NY, and another in
> Sweden. Which all goes to show that copper
> minerals can replace oganic matter quite easily,
> in a wide range of environments. Fascinating.

Hi all,
copper secondaries (and also primaries ;-) ) after or on fossil wood are not really rare. As David pointed out the reducing environment of C-org bearing material is a favour to precipitation of metal sulfides etc. if in contact with e.g. sulphate bearing solutions. It is very common here in the Nahe region copper mines that old wood fragments are mineralized with recent/subrecent copper secondaries .. but it is also common that fossil permian wood has replacements or overgrowths of copper minerals. Nothing unusual,

cheers
Roger

My dad was a geologist in west Texas. I have several pieces of malachitized wood he collected years ago at a place called Buzzard Peak in the Texas panhandle. I know of 2 other locations. Mike Streeter does a field report over at MCrocks.com on a location in southern Oklahoma with photos. Also I have a friend in Taos who is currently mining the same near Cuba, New Mexico. Dave Owen