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A black pertified wood?


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It does not appear to be petrified wood. 

I wonder what other basic observations we could make to try and identify this specimen?

I wish there was something we could do to give us clues about the composition of this rock.

:idunno:

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No. They just don't look anything like an agatized or opalized wood.

I wish there was some basic test that could be done to help identify your stones. Some simple observation to shed some light on their composition.

Alas, I am simply stumped at what could be done to identify these rocks.

I wonder if you could determine if there were oxidized minerals in the rocks by creating some sort of fine powder and observing the color? It seems like it should be possible with some sort of abrasive. 

I know it is a wild idea. But surely there must be some simple test that could help identify these rocks.

I read on the internet somewhere how guys would rub a rock against a hard, abrasive surface. I think they said it may give clues about the rock.

The same guys would weigh the rock dry, and then again in water. Im not sure why, but it was something about density. Maybe that would help someone determine what the rocks were made of?

I know petrified wood is silica with really small crystals. Im wondering if a magnifier could be used to evaluate the matrix and offer some clues?

I wish someone had developed some sort of process for this. You would think there would be some sort of established method to identify rocks by now. I'm just completely stumped on what they may be though. 

:idunno:

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51 minutes ago, Bedrock Bob said:

It does not appear to be petrified wood. 

 

3 minutes ago, Bedrock Bob said:

No. They just don't look anything like an agatized or opalized wood.

I wish there was some basic test that could be done to help identify your stones. Some simple observation to shed some light on their composition.

Alas, I am simply stumped at what could be done to identify these rocks.

I wonder if you could determine if there were oxidized minerals in the rocks by creating some sort of fine powder and observing the color? It seems like it should be possible with some sort of abrasive. 

I know it is a wild idea. But surely there must be some simple test that could help identify these rocks.

I read on the internet somewhere how guys would rub a rock against a hard, abrasive surface. I think they said it may give clues about the rock.

The same guys would weigh the rock dry, and then again in water. Im not sure why, but it was something about density. Maybe that would help someone determine what the rocks were made of?

I wish someone had developed some sort of process for this. You would think there would be some sort of established method to identify rocks by now. I'm just completely stumped on what they may be though. 

:idunno:

What about this rock?16300800222506620591052031478935.jpg16300800925884408488483396597106.jpg

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We really need to work on the process.

If you give a man a fish he will eat for a day. If you teach a man to identify rocks his toilet tank lid will be destroyed.

It kinda looks like quartz in some type of schist to me. But identifying rocks from nothing more than a photo is probably not very accurate. 

:)

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Agreed ×100*

15 minutes ago, Bedrock Bob said:

We really need to work on the process.

If you give a man a fish he will eat for a day. If you teach a man to identify rocks his toilet tank lid will be destroyed.

It kinda looks like quartz in some type of schist to me. But identifying rocks from nothing more than a photo is probably not very accurate. 

:)

 

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Sketch, your last sample photo appears to show the mineral Sillimanite (white minerals).  It is a real beauty if it is Sillimanite.

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Here is a stone that I think is very similar to yours. I thought it may be some type of asbestos mineral. It could very well be sillimanite. It is a very similar material to asbestos.

It has the same radiating, fibrous looking patterns. And the host rock is similar.

It is in mica schist from Northern New Mexico.

 

20210827_162301.jpg

 

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Bob, it would be cool if you made a list of things to do before asking for further ID ON ROCKS AND MINERALS like a guide then the streak test etc would be listed with the question 

I’ll pin it here

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That's a beauty of an rock you have Bob!  Looks like it is made up of labradorite.  The fibrous mineral(s) could also be Rutile.  Did it come from New Mexico?

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43 minutes ago, 4meter said:

That's a beauty of an rock you have Bob!  Looks like it is made up of labradorite.  The fibrous mineral(s) could also be Rutile.  Did it come from New Mexico?

Yes. It is from the Sangre de Christo range.

It is the standard mica schist that is so common in that area. Im not sure about labradorite... We find that here in some volcanics in the south. But it might be some form besides the blue schiller labradorite im used to collecting. 

This was a river cobble that stood out. I picked it up wondering what the fibrous stuff was. When I realized a bunch of the river stones were the same I figured it was asbestos or some similar mineral. Im convinced it is an aluminosilicate. But I could certainly be wrong. 

There is a ton of the stuff near the village of El Cerrito, New Mexico. There is mica schist outcrops everywhere and in places it gets shot full of this stuff....whatever it is.

There is a quarry they mined material to make fire bricks not too far away. I think they mined aluminosilicate. I assumed this was what this was but that is just an assumption.

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I've collected very similar material Bob. Most was found on the higher benches on the north side of the Pecos between El Cerrito and Villa Nueva and one small piece further upriver near Sena and a nice specimen near Tommy's place in Ribera. The material all appears to be water worn. I believe the schist there is in the Khondalite group which often includes Sillimanite mineral.

Your piece is very attractive and bluer than most of the material I collected. I have found some deep green translucent pieces as well. I believe the crystal sprays are Sillimanite but the base material seems to include several other interesting minerals that I have yet to positively identify.

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There are a bunch of guys here that have seen a bunch of rocks. Sometimes all it takes is one photo and five guys will all agree. But often you just can't ID a rock from a photo. You have to know a few things that a photo just can't capture.

So here are a few tips to rock and mineral identification.

 When trying to ID a rock or mineral from a photo it is important to have good photos. A couple taken in natural sunlight at different angles is good. Photos taken inside under lights often don't capture what we need to see.

A close up is also good. Quality photos that are zoomable really help. We need to see the individual crystals in many rocks and this can't be done without a good close up.

The streak test is the basic test for mineral ID. When you provide a streak color it will help to identify the mineral and also give us a clue about hardness. Here is a good explanation of the streak test-

https://geology.com/minerals/streak-test.shtml

If you don't do a streak test someone will tell you to go rub the rock under your toilet tank lid. You can do this. But it will really help to understand what a streak test is and how to do one before you go rubbing rocks on your toilet.

You should also tell us how heavy the rock is. You dont need to be too technical. Just tell us if it seems heavy or light compared to the average stone. A specific gravity can be helpful but it is difficult to perform accurately and is not always needed. Just tell us if the stone seems heavy or light for its size as compared to "other rocks".

Wave a magnet over the rock and tell us if it is magnetic. This is a simple test and will often be the info we need to identify the rock. 

Hardness is important too. Try to scratch the specimen with a nail. Try with a piece of glass. Better yet try to scratch it with a known mineral like quartz or feldspar. This information can often narrow it down.

If you can provide good photos of the overall stone, a good close up photo, a streak color, a weight estimate and a wild guess as to hardness we can offer some pretty good guesses. If we can't we might suggest some other simple test.if you provide the simple information needed you will usually get some very good answers and learn a lot about the identification process.

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23 minutes ago, clay said:

I've collected very similar material Bob. Most was found on the higher benches on the north side of the Pecos between El Cerrito and Villa Nueva and one small piece further upriver near Sena and a nice specimen near Tommy's place in Ribera. The material all appears to be water worn. I believe the schist there is in the Khondalite group which often includes Sillimanite mineral.

Your piece is very attractive and bluer than most of the material I collected. I have found some deep green translucent pieces as well. I believe the crystal sprays are Sillimanite but the base material seems to include several other interesting minerals that I have yet to positively identify.

Bingo.

The stuff is all over in the El Valle area and down river towards El Cerrito. In the river gravel. 

There is a pit above the Ribera exit off 25 where the schist comes through the sandstone. The vato that I talked to said they mined fire bricks. I figure he could be talking about some refractory material. 

It all tops out above Tecolote near Barro Peak at mica canyon. That green mica schist turns into a pegmatite with fat mica books and columbite crystals. 

North of there the mica schist kinda goes toward Las Vegas and the pegmatite and mica/monozite stuff splits towards Elk mountain. That is right above the Preist Mine.

All that sandstone up there is that deep blue green just like the schist. The schist looks like big chunks of wood sprinkled with mica. You can hardly tell the rocks from the rotten logs in Mortandad canyon. Where that stuff sits next to the pegmatite it gets hard and shows all sorts of wild minerals.

I figure that is where these rocks originated. Way up in some schist outcrop next to that pegmatite above Tecolote. It's straight down Mortandad canyon about 6 miles to El Valle where all of those river stones are laying around.

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On 8/27/2021 at 4:03 PM, Nugget Shooter said:

Bob, it would be cool if you made a list of things to do before asking for further ID ON ROCKS AND MINERALS like a guide then the streak test etc would be listed with the question 

I’ll pin it here

That would be great to identify minerals Bill. Minerals can be positively identified by doing some pretty simple tests. Any given mineral will always test the same no matter where it was found. Minerals are very well defined. Bob knows this stuff well so he would be a good choice to make that post if he's so inclined.

Rocks on the other hand can not be positively identified by simple tests. Rocks are composed of minerals but often those minerals are "included" and do not help with a positive identification of a rock. Although knowing the specific gravity and hardness of a rock can help narrow down what type of rock might be involved those tests naturally produce very different results often within each rock itself. Mineral test results do not vary for any particular mineral but the same type of rock will almost always have very different test results.

So even though a mineral specimen may appear to be the mineral hematite and a hardness, specific gravity and streak test shows that it is indeed hematite a rock that appears to visually resemble hematite but fails one or more tests for hematite only demonstrates that it is not hematite and gives us no reliable information about what the rock actually is because rocks do not have defined repeatable tests to establish the rock type. Streak, hardness and specific gravity do not provide positive identification of rocks because they are not consistent in rocks where in minerals they are consistent.

Bob shows some schist in his example. Schist is a rock that varies in hardness between talc and garnet depending on how it was formed and how far it's eroded both chemically and physically. It comes in every color of the rainbow and may contain many different combinations of minerals that can only be generally grouped into classes of combination of minerals. Schist rock specimens will vary from location to location even within the same formation. Some other very common rock types are graywacke, basalt and grabbo, none of which can be defined by any of the common mineral tests.

An experienced rock collector can often pinpoint the location and type of an unusual or collectable rock by it's appearance alone. Certain well known jasper and agate (rock)deposits come to mind like Biggs Jasper or Lake Superior Agate, I'm sure you can think of others, but this is more the function of a visual ID associated with long experience rather than a test that could provide a positive ID.

There's nothing wrong with describing rocks by texture, color, density and hardness to help viewers understand what they are seeing in a picture, any info helps in this situation but it's a hopeless task to try to positively identify a rock by these common mineral tests.

So with rocks we are left to explain them as defined by their method of formation and the chemistry present when they were formed. A properly used XRF can provide valuable information about the rocks chemistry and knowing the way the local base rocks were geologically formed can help identify which basic type of rock is being tested.

I too think that a pinned post defining how to test for mineral IDs would be a big help but lets not confuse the issue by including "tests" for rocks.

Edited by clay
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Just now, Sketch said:

I think that the first photo that I uploaded seems to be a fossilized tree fungus or mushroom.

And It also has one of the most unsual texture i have ever found because it has a wooden texture but it is a hard rock.

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40 minutes ago, Sketch said:

I think that the first photo that I uploaded seems to be a fossilized tree fungus or mushroom.

It does kind of look like a fungus. Fossilized? I've never heard of that happening. Doesn't mean it hasn't but I don't think it's the obvious explanation for your perception of a "fossilized tree fungus or mushroom". It happens with clouds and tree trunks and rocks and it's called Pareidolia. It makes the world more fun and interesting and as far as I can tell all humans have experienced it including myself just now.

 

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41 minutes ago, clay said:

It does kind of look like a fungus. Fossilized? I've never heard of that happening. Doesn't mean it hasn't but I don't think it's the obvious explanation for your perception of a "fossilized tree fungus or mushroom". It happens with clouds and tree trunks and rocks and it's called Pareidolia. It makes the world more fun and interesting and as far as I can tell all humans have experienced it including myself just now.

 

That's why I was  surprised too. It has looks and texture like fungus but it  is a rock.

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