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Petrified wood?


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Yep, it's me again.  This time I have a rock I found that looked like burnt wood so I figured petrified wood, but, it didn't seem to have any wood like features inside like all other petrified woods I've found. Like rings and junk.  It weighs like 7 oz roughly. It was proving difficult to get a streak on the porcelain so I ran it across my diamond Rock and I believe it is gray.  I cut it in half to see the inside so the flatter side in the pictures will be the inside.  I can't exactly remember but I don't think the magnet cared for it either.  thanks for any info I do enjoy the education, and I'm sorry for posting so much.

 

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That's a cool little piece cut like that.  Save some for a comparative collection. I think it's probably quartzite - metamorphized sandstone (partially melted) with the grainy texture still intact. If it was fully melted and glassy, it would have been obsidian.  And as you found out, it is very hard and does not streak well.

Don’t apologize for posting these, it's great practice for all of us geology students!:D

Edited by GotAU?
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The texture in the last couple photos do look like wood. But it is really difficult to tell. 

Wood agate can be just about any color. And sometimes it doesn't look anything like wood. 

It's more about the crystalline structure of the material. Whether it is glassy or sugary in texture and how it flakes off when chipped. Agates and jaspers are "in between" glassy obsidian and crystalline quartz. They are not quite glass but pretty darn close. They flake with a conchoidal fracture but at steeper angles than the glassy stuff like obsidian and opal. 

What you have does not look glassy enough to be petrified wood. But it certainly could be. It is definitely a silica rich rock but the texture indicates it is coarser grained than an agate and probably formed under a bit more pressure than an agate would form.

I bet if you look closely with a magnifier you will see the crystal structure on the surface of a fresh break. It won't look glassy and smooth but frosted and a bit textured. That will tell you whether the rock is microcrystalline like an agate or crystalline like a quartzite. If it is frosty and crystalline it is not petrified wood.

 

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I see absolutely no signs of it being petrified wood. It will not streak as well. I'm just not sure exactly what you do have other then it contains silica.😉

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