Rock identity?

[Roy1]

Moderately heavy rock ( not volcanic) with very rough surface, with interesting inclusions. Found in Osage River valley (an arm of Lake of the Ozarks) in Benton County, MISSOURI ( west central MO). If anyone has an idea what this is, I’ll send more pictures.

[Rockwood]

Tufa ?

[grandpa]

^{Well Roy, I'm seeing a couple of oysters on the right hand side of the matrix.  As for the other 3 items, I don't know your area enough to proffer a speculation based on the partial preservation of these items.}

[Roy1]

Thank you for that. I see them now that you mentioned them. The other on the left may be another from side-on.

We are on the edge of the Ozark Highlands. I’m told the hills and valleys are due to erosion and not uplift.

[Roy1]

2 hours ago, Rockwood said:

Tufa ?

Thanks. May be. It’s rough without being real porous. 

[Ludwigia]

The rock looks very weathered, but maybe the reverse side can give us some more clues as to its make-up. Could you post a photo of it?

[Roy1]

Sure. Here it is.

[grandpa]

How fun!  I think we have a coral on the reverse side.  Can you provide a close-up of the lower left quarter of the specimen where the structure looks like coral cells?

[Roy1]

Bottom side shows a break

[Roy1]

Sure. Here it is

[Roy1]

[Rockwood]

I don't think that is coral. Rather I believe it to be inclusions of oolitic limestone.

[Jackson g]

I agree with @Rockwood, I don't think thats a coral either. The rock looks like a mix of hard, cherty limestone. I have found nice pieces I've kept with oolitic and druzy inclusions, just like yours. If I can remember I'll share one later on after work I've found in the area.

[Ludwigia]

Yes, I was thinking oolite as well now.

[Roy1]

Thanks to all for the information. I appreciate each of the responses. Now I’ll go google Oolite to learn more.

[Ludwigia]

1 hour ago, Roy1 said:

Thanks to all for the information. I appreciate each of the responses. Now I’ll go google Oolite to learn more.

There are a number of oolite types, but this looks like iron oolite to me.