Does anyone know

I don't remember a mine ever being mentioned in this manhwa. I'm so confused!

The mine was originally the dukes, but confiscated by the emperor for some petty reason I can’t remember and mined dry. However the duke wants it back because he knows the actual value of it (it has some rare hidden material). He was originally gonna use his merits from the war to get it back, but instead asked for marriage to FL.

Due to a deal with the princess FL now has ownership over it (but I don’t think anyone knows this yet). So the princess is shitting herself right now since the emperor has somehow caught whiff of its potential and wants her to report about it to him when she longer has the rights to it.

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the mine was originally owned by ML's mom, she used to be a princess from a fallen kingdom (mine was her inheritance). So the King is a piece of shyt who desired ML's mom coz she's beautiful, he sent ML's dad in a war but originally the people that accompanied by dad was on king's side and they betrayed him, then the king blamed the duke for "losing" the war, the royal family confiscated the mine as payment and confined the duchess in the castle coz he wants to Fvck her, i don't know if he did F her but she died i think by poison or depression? i don't remember, but until now he still have her portrait in his room.
the mine produce important and rare stones, it's like mana stones but something purer and valuable (imagine having your own nuclear reactor), up to now, the mine was dry. in official paper, it's just a simple dry mine, but they know there's something magic in there so they are sending mages to check things.

Thanks, your post helped me remember!
Yeah it’s unclear if he’s the kings son or not. Like it made it seem like he was since king took the duchess and SA her while the duke was away. She commits suicide some time after ML is born right, and the duke raises him as a single parent. The weird thing is that ML looks exactly like the former duke. So is he the kings son, or was the duchess already pregnant when the king confined her?

no, ML is already around 10+ when it happened, that's why he spent his whole teenage years in the battlefield coz he became duke very early

Oh for some reason I thought she died before the duke. I guess I’m mixing up my stories

well that can be a good plot point on other stories lol