Hello and thank you for answering.
I will agree with your opinion that the stone from the last photo looks like an earth rock, I kept it because there is something interesting in it.
![Smile :)](./images/smilies/icon_e_smile.gif)
Which university do you mean, where can I show the stones? Or where to send samples for a reliable analysis of pebbles?
I add some photos of thin sections of stone.