What is this rock ?

[ivobg]

Quite heavy for its size, it has little sparkles and its not magnetic

 

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[Ponchosportal]

Appears to be low quality petrified wood.

 

[ivobg]

Appears to be low quality petrified wood.

Didnt expect that
Checked some pictures on google and it looks like you are right
Thats something new for the collection

 

[Eu_citzen]

I would have guessed either siltstone or mudstone.

 

[Ponchosportal]

I would have guessed either siltstone or mudstone.

I agree except the bedding would be to complex and what appears to be the presence of SiO2?

 

[ivobg]

Cheked pictures of siltstone and mudstone, but petrified wood looks more close to it

 

[Eu_citzen]

I agree except the bedding would be to complex and what appears to be the presence of SiO2?

Look at the first and last pic. Bedding looks simple enough.
Some presence of quartz is not unusual; in fact this is what made some of these useful for sharpening knives! (I use one in the kitchen; sharpening stone)

The unusual look might be due to some layers being more resistant to erosion then others. Thus the odd look.

 

[stdenis_jd]

best bet is to do a hardness test on the non-weathered part of that rock, should be really close to 7 (6.5-7) as pet wood almost completely replaces its organic material with silica if I'm not mistaken.

 

[Ponchosportal]

Look at the first and last pic. Bedding looks simple enough.
Some presence of quartz is not unusual; in fact this is what made some of these useful for sharpening knives! (I use one in the kitchen; sharpening stone)

The unusual look might be due to some layers being more resistant to erosion then others. Thus the odd look.

There is nothing simple in bedding of the third photo. Nor is the deposition consistent with siltstone or mudstone.

The unusual look is absolutely because of slight differences in the competence/composition of the material resulting in the erosion you describe.

 

[Eu_citzen]

There is nothing simple in bedding of the third photo. Nor is the deposition consistent with siltstone or mudstone.

The unusual look is absolutely because of slight differences in the competence/composition of the material resulting in the erosion you describe.

The third pic to me looks like it might indicate (low grade) hydrothermal alteration. If so, depositional characteristics might have been altered.
Note: perhaps I was mistaken on the other pics and we're seeing cleavage. (rather then bedding)

A Siliceous mud- or siltstone will also pass the hardness test if enough silica is present. (though likely thus bordering on sandstone?)

The 'grainy' and porous nature of the rock suggest sedimentary origins to me.