Any help would be appreciated.

[Vickie B.]

I found this over the weekend at a rock quarry in west central Minnesota.  I just cannot find out what it is. Can anyone help me? It's not magnetic and weighs what I feel it should, for the size. 

 

  

[JimB88]

Looks like a weathered coral of some kind

[Al Dente]

It looks like Cretaceous pisolitic clay that occurs in Minnesota. I was told at one time that this was bauxite but it lacks the high amounts of aluminum that bauxite has. I have several pieces that I found in Iowa that were glacially transported from Minnesota. I'll take a photo later today. It looks nice cut and polished.

[Al Dente]

Here are some photos of my nicer piece.

 

 

[Tetradium]

5 minutes ago, Al Dente said:

Here are some photos of my nicer piece.

 

 

guess they don't end up in twin cities. I had found nontwinned starolite and plenty of mica which seem to show glaciers moved them from an bed on upper Mississippi river. Book listed one outcrop of mica with starolites on it in one spot up north but I hadn't visited it. 

9 minutes ago, Al Dente said:

Here are some photos of my nicer piece.

 

 

bauxite is usually deposited in tropical climates. Due to the high temperatures during cretaceous period I'm guessing similar types of deposits but maybe because of higher latitudes its different somehow?  

[Tetradium]

13 minutes ago, Al Dente said:

Here are some photos of my nicer piece.

 

 

After all it look like a ton of little nodules with black being some other kind of heavier minerals. Only a tropical climate with high rainfall rates makes that kind of deposits, leaching aluminum, etc. down deeper in the soil. 

[Ludwigia]

1 hour ago, Al Dente said:

Here are some photos of my nicer piece.

Very pretty! Never heard of this before.

2 hours ago, Vickie B. said:

I found this over the weekend at a rock quarry in west central Minnesota.

That sure is a nice specimen.