[GS] vs 1.0.0.328 Eureka Issue

[Timothy001]

On turn 238, got the Great Admiral that gives a free Ironclad(Yi Sun Sin). On Turn 239, I used a builder to place a mine on a hill. It unlocked the Eureka for Steel (Build a coal mine and an Ironclad).
However, I haven't discovered Industrialisation yet (Haven't revealed coal).
I'm convinced that when I do reveal coal, it will be on that tile.
My issue, the Eureka should not be given until coal is revealed.

 

[Timothy001]

Update. The hex did contain Coal.

 

[Rosty K]

Yes, that's how it is. Once you get a resource from somewhere, it's considered that you have revealed it. Something similar happened to me with niter - I swear I had none on my territory, but then I discovered the tech, and started getting it from Hattusa. It gave me the Rifling eureka (or maybe things were slightly different, don't remember exact details, and don't have a save...