Misterious Volcanic Rock?

[IamCurious]

Hi, so today out in a nearby field i found this rock which looks volcanic to me, but i dont have much experience...
Its was found in a field near a city which doesn't have any volcano activity there or even close, in fact the country (Portugal) does not have or had any active volcanoes.
The rock has some shine to it and some iridescent in certain areas.
Please help , i am curious.
Thanks

 

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[Jason in Enid]

industrial slag.

 

[Tuberale]

Welcome to TNet, IamCurious. Don't know what part of Portugal you are in. Also don't know if you have "industrial" area nearby. Are there?

 

[IamCurious]

Thank you, This was found in Évora. There is no industrial area nearby at all, the stone was found in the old unused train tracks that were used by a cereal factory that shut down in the 50s

 

[Johncoho]

Looks like cinders from coal that was burned in the old locomotives to make steam to run the train.