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FossilsPetrified Wood-Utah

26th Jan 2021 22:31 UTCBurch Elliott

Hello,

I recently found a rock that i believe to be petrified wood, I’m not sure what minerals are involved in the overall specimen, but there was a lot of sediment, clay, and hardened dirt caked on the rock. I have washed the wood several times over with warm soapy water with a toothbrush and can’t seem to get the last bit off. Hoping y’all would have some helpful tips on how to properly clean this without harming the wood. I’ll add a picture of what the wood looks like currently.

Thank You!

27th Jan 2021 00:04 UTCPaul Brandes 🌟 Manager

Welcome to Mindat, Burch!

Pet wood is pretty resilient, so you could use a stiffer brush on it to continue which may help. Dow Scrubbing Bubbles also works well to loosen up caked on mess and is fairly safe to use.

27th Jan 2021 00:19 UTCSteve Ewens

Burch

If the wood is mainly carbon that black is not going to come off. From your picture it looks like the black is also on the ends. Often, petrified wood will bleach color on the outside.

Pieces that have a high silica content (agate and jasper) are the ones that will take a polish.

Very interesting to find though.

Steve

28th Jan 2021 18:26 UTCBurch Elliott

I should have clarified, I am more looking to get this clay like sediment off of the wood. This is what i believe to be the bark side of the wood and the dirt wraps around the bottom to the opposite side.

27th Jan 2021 08:38 UTCErik Vercammen Expert

To be sure that this is indeed petrified wood (very probable) a pic of the upper or under side of the specimen will be helpful.

28th Jan 2021 18:30 UTCBurch Elliott

Here’s another photo of the wood, I apologize for the quality, my phone isn’t quite capturing the detail I would like it to be.

27th Jan 2021 18:13 UTCDaryl Babcock

It looks like the stuff I used to collect down around Kanab, lots of that and even more bleached out white stuff. As less than a novice I tried to clean mine up as well, so I think I know what he is talking about. The pinkish stuff and the "sand grains" that are firmly stuck.

I am pretty sure the sand grains are crystal growths (my guess quartz) because they leave a divot if you do get them to release. They are intergrown, not just stuck on by mechanical means. As for the pinkish stuff, no clue what it is but it takes a grinder or chisel to remove.

That is a nice piece of southern Utah petrified wood. If you want something shinier, more colorful and with no sand grains or pink stuff cross over to St. George, there is some nice P wood there.

28th Jan 2021 18:52 UTCKevin Conroy Manager

This may be a mineral deposit on the wood. Put a few drops of muriatic acid on the deposit and the petrified wood. It shouldn't effect the wood at all. If bubbles form on the deposit, it's a carbonate mineral of some sort, which can be removed with a longer soaking in a solution of water and muriatic acid. If the deposit doesn't bubble with muriatic acid, then I'm afraid you may have to leave it as is.

28th Jan 2021 18:59 UTCAllan Blaske

Just going out on a limb here (pun intended!), but as i see it there are several possibilities. I'm no expert in Utah petrified wood, so these are general suggestions. I assume that the wood has been fossilized and replaced by silica (quartz). A quick hardness test will confirm this.

If the pinkish material is actually clay, you could try soaking it in some hydrogen peroxide (more concentrated than the drug store variety). Often times the hydrogen peroxide bubbling action can loosen material like hard clay.

But I suspect it is not clay, since you have already been scrubbing with brushes. It is more likely some sort of mineral growth.

Perhaps it is calcite. Try a test with hydrochloric acid and see if it fizzes. If it is calcite, a soak in acid will remove it from the wood without damaging the petrified wood.

Perhaps it is microcrystalline quartz (chalcedony). It could be a later generation of silicon dioxide which seeped into (via groundwater) the cracks in the rock after the initial fossilization. If it is microcrystalline quartz, there probably isn't a way to remove it.

Good luck!

8th Apr 2021 20:02 UTCsteven culbreth

Yes, it would seem that he is trying to remove material that mineralized along with the wood. Could be some fungus that was growing on the wood before petrification.

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