Cannot mine gems

[GMO]

I'm using CIVUP 2.5.2, GEM 1.13.4.

I've researched mining but I can't mine gems. There is no option to mine them when I have workers on the gems tile.
I should be able to mine gems with mining.

 

[mystikx21]

Is the tile forested/jungle?

 

[GMO]

yes, jungle, which , I think, means the jungle has to be cleared first, then the mine.

Thankm you.