conglomarate of rock

[mclean]

Here is a rock I found in a river, I believe it is a conglomarate of iron crystals and other minerals, has anyone seen a rock like this and I would be very interested to find out how it was formed, thankyou.

 

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[bologna321]

That is very interesting, I've seen a lot of rocks and I have no idea.

Looks like slag or some kind of igneous rock that cooled before all the rocks it intruded into melted. I'm just throwing out wild guesses.

 

[Kray Gelder]

If it's iron it would attract a magnet. The cubic crystal forms suggest pyrite or galena crystals. The color of the cubes may indicate oxidized galena in sandstone or mudstone. IMHO.

 

[Professor of Engineering]

Very interesting rock find!

 

[A2coins]

looks really. cool

 

[paleomaxx]

Definitely pyrite (iron sulfide) crystals in a slate matrix. Here's a sample freshly broken from the host rock:



Your sample is particularly cool though as that's the first I've seen as a river rock. The water action wore away the slate faster than the pyrite leaving distinct crystals with just a little edge smoothing. That's a great display piece you found!

 

[Kray Gelder]

Definitely pyrite (iron sulfide) crystals in a slate matrix. Here's a sample freshly broken from the host rock:

View attachment 1610888

Your sample is particularly cool though as that's the first I've seen as a river rock. The water action wore away the slate faster than the pyrite leaving distinct crystals with just a little edge smoothing. That's a great display piece you found!

Defintely? Wow. The example you post does not resemble the OP's.

 

[niffler]

Agree, mudstone.

If it's iron it would attract a magnet. The cubic crystal forms suggest pyrite or galena crystals. The color of the cubes may indicate oxidized galena in sandstone or mudstone. IMHO.