Possible fossil?

[saracakes3889]

Hello everyone hope everyone had a great Thanksgiving! My father got to work yesterday and found this during their construction job. He said it was 9ft underground and says that the black sphere is heavy like metal and popped right out of the rock. Is this a fossil? Thanks for any tips! 

[Rockwood]

Fossiloid 

Looks like a septarian concretion.

[Tidgy's Dad]

Yes, an ironstone concretion, I think. 

[Rockwood]

I used the term fossiloid to suggest an association with fossils. You sometimes see them in the same museum.

[ynot]

I agree with an iron concretion.

[FranzBernhard]

Yes, this is an iron-rich concretion. Do you have more of them? Could you open up one of with a hammer or with a tile saw?

It is clear that these are iron-rich concretions (heavy!), but I am not sure if they are composed of siderite (iron carbonate) or pyrite/marcasite (iron sulfide).

I see that you are from northern Texas, are you able to pinpoint to which formation these rocks belong? In this way it could be possible to get more info about the composition of this concretion without destroying it.

Franz Bernhard

[Rockwood]

6 hours ago, FranzBernhard said:

pyrite/marcasite (iron sulfide).

The weight would seem to indicate this. I can see the septarian look being a remnant of lighter matrix.