Jet?

[kerrimarie805]

Petrified wood? Jet? Is jet petrified wood? Can someone explain the specifics please?

[FranzBernhard]

28 minutes ago, kerrimarie805 said:

Is jet petrified wood?

No.

Jet is a form of coalified wood, composed essentially of C, H and O.

Petrified wood is wood replaced by minerals, most often a SiO₂-based mineral (quartz, opal). So its is often essentially composed of Si and O.

 

Concerning your specimen:

- Is it lightweight for its size? Jet has a specific gravity of around 1.3. Petrified wood would be around 2.6 (neglecting any porosity).

- What happens if you put a fragment in flame (lighter, candle)? Please wear goggles.

- Try to scratch it with a nail. What happens?

 

Based on your pics, I can not totally rule out some kind of slag, though.

And a piece of river-tumbled anthracite can also not be ruled out!

 

Franz Bernhard

Edited August 10, 2021 by FranzBernhard

[kerrimarie805]

I did try "writing" with it and left no color behind nor mark other than my tearing the paper, the slightest scratch on the back of the ceramic tile.

I will try the other tests now. Thank you.

And may I just say, I want to thank all y'all! I am so glad to be back here, I don't know why I didn't do it sooner. So I thank you for putting the time into this forum and what you do, thanks for spreading science-ey knowledge, thank you for not being Insta-chat-face! Full disclosure: I do love Instagram, yes I do. A discussion venue it is not, tho.

Sincerely, thank you.

 

PS.  Franz, when you say "burn," what exactly do you mean? Heat up the end of a pin or get out the blow torch?

I have at least one more piece of what looks like the same material. Shall I post pics of those, too?

[Rockwood]

1 hour ago, kerrimarie805 said:

Franz, when you say "burn," what exactly do you mean?

I was glad to see Franz explain things. All I can picture is the Muppet character Beaker with his Bunsen burner.  Sorry.

[FranzBernhard]

3 hours ago, kerrimarie805 said:

Heat up the end of a pin or get out the blow torch?

Take a small (<< 1 cm) fragment with a pair of tweezers and hold it into a flame of a lighter or candle. I am seeing a lighter, somewhere . You can hold the fragment also in the flame of a blow torch, of course .

 

3 hours ago, kerrimarie805 said:

the slightest scratch on the back of the ceramic tile.

Jet and most other coals would not write on paper. What happens in detail when you rub it on the back of the tile? Does it leave a "streak"? Would you like to provide a pic of the "streak"?

 

2 hours ago, Rockwood said:

All I can picture is the Muppet character Beaker with his Bunsen burner.

Now you have to define who is who .

 

Franz Bernhard

[Rockwood]

24 minutes ago, FranzBernhard said:

Now you have to define who is who

It's just how the procedure is filed in my head I think. If I ever grow up I'll be lost.

[FranzBernhard]

7 minutes ago, Rockwood said:

If I ever grow up I'll be lost.

 (I know that!)

Franz Bernhard

[daves64]

6 hours ago, Rockwood said:

I was glad to see Franz explain things. All I can picture is the Muppet character Beaker with his Bunsen burner.  Sorry.

 

[kerrimarie805]

I have heard the Beaker bit before, I'll own it! Not to worry, I will try not to blow anything up...probably. 

I have science homework to do now, will get pics.

[kerrimarie805]

Okay, here's what I got...

It's fairly weighty for it's size and hard as a rock. Lol! I tried chiseling a piece off for the burn test and didn't make a mark on it aside from chipping it. 

I scratched it with a file and it left only the metal smudge as evidence, no scratch on the piece. X marks the spot in the first photo, but it's very faint.

I smudged two pieces of ceramic tile and one piece of crockery. It did leave marks similar to a very hard drawing pencil, no scratch, and it wiped right off with my finger. I may have to post these photos in another reply box.

As well, the burn test results will follow.

[kerrimarie805]

Smudges

[kerrimarie805]

The burn test also did almost nothing to the piece. I heated a spoke and held it to the piece, x marks the spot, and got no result. So, I took the torch to the end of the point and kept it there until I saw something happen. It took over a minute, but it did get hot enough to faintly glow orange. It didn't glow hotter than pictured so I took the flame off after 2 minutes. There was no change as a result of the heat or burn. No odor or smoke, either. 

Hard as a rock, I tell ya!

Before

Burn

After

[FranzBernhard]

Good work, @kerrimarie805!!!

 

Its clearly not any kind of coal, jet etc.

 

The new pics suggest, that it is somewhat translucent?

 

I am still very uncertain, what it really is. Some kind of chert/flint/chalcedony? The grey smudge is not in favor of that!

 

I still think it could be some kind of slag. Upon close inspection, do you see any small voids or bubbles? There could be a few, but I am uncertain!

 

Ah, do you have a magnet? Is ist somewhat magnetic? The grey streak may come from some admixed magnetite, but that´s only a hypothesis .

 

Franz Bernhard

[kerrimarie805]

I agree now that it is definitely not jet. As well, I can submit that it is not slag. It's not porous at all, nary a pocket nor hole in any of the 3 pieces I've found, and quite even colored black. There is quite a bit slag in the same area, in and around a lake, but it is most certainly a different material. I'm not sure what you're seeing in the pics that indicates it might be translucent, it is not, not even a hint around the edges.

So...not jet, pet wood, slag, or jasper (no light gets through around the edges and I can't chip it so I'm ruling out jasper). I'd spur you, Franz, to continue this topic with me in order to ID the material, but at this point my question has been answered. Whatever it is, it doesn't belong in the pile of pet wood, it has to go sit with the other rocks in the rock garden. One more question, tho, what kind of rock would be hard enough that I couldn't chip it even a little bit with a chisel and hammer?

I posted three other pieces that I am currently fixated on identifying. Would you mind taking a peek at those as well if you haven't already seen them? Thank you, Franz and Rockwood, for your knowledge and time, and Dave for the Beaker bit. You get me, somehow, lol!

 

Oh, heads up--I am posting the piece that has be logged in here again after so long. I would love for y'all to lmk what you think!

 

Rockin', 

K

 

 

[FranzBernhard]

11 hours ago, kerrimarie805 said:

what kind of rock would be hard enough that I couldn't chip it even a little bit with a chisel and hammer?

Thanks for the extra info!

 

Its about toughness (link to wikipedia). Some quartz-based rock can be quite tough. But based on your results (it leaves a grey smudge on a tile), I don´t think its a quartz-based material.

From my experience, some dolerites/diabase (altered volcanic rocks) can be extremely though. You can hammer the hell out of it without breaking them. But it doesn´t look like this, your specimens are too glassy-looking.

 

I am still in the slag-camp. Some slags can be quite homogeneous and void-free. In some areas, slag was (is?) also cast into bricks. And slags can also be quite tough, depending on the cooling and crystallizition history of the slag. In my area, slag from a small steel work is used for road construction, for example.

 

So, at the moment, these specimens will remain a mystery.

 

What you still can do is to determine specific gravity. The beaker needed is already there !

 

Franz Bernhard