District - grayed out question

[Time and Tactics]

Just got back into Stellaris and have a question about districts.

In the picture, there is one potential mining district that is grayed out. Why is that?
This is the United Nations of Earth default start.

 

[sillyrobot]

One of your blockers is covering it -- click on the picture below your drawn arrow with the yellow/black border (which I now note you have) and check each individual description.

 

[Hecktor]

You got 16 districts in total. There can only be a maximum of vertain districts beside city ones.

You got 3 city, 2 generator, 2 mining, 2 farm and 3 clearblockers. Thats a total of 12 which let you remain 4 districts to 16 (planet maximum).

Also e. g. if you'd have 10 city distrcits the 7th mining districts would be greyed out either because you would exceed the planet maximum.

 

[Kareal2]

Because you can only build 4 more districts(with current blockers reducing the max by 3) so there are 4 colored ones of each type and the rest are Grey.

 

[Time and Tactics]

Thank you Hecktor and Kareal2!
So, the planet has 16 max districts. 3 are currently blocked (right side of the picture).
I have 9 district that have been built. That leaves 13-9=4 districts that can be built.
Any remaining potential district in each category is marked as grayed out.

I removed the Great Pacific Garbage Patch (which increased the Agricultural districts by 3) and there are now 5 districts available to be built in each category (as I expected).

 

[Hecktor]

Yup, industrial wastelands would unlock the other 2 remaining generator distrcits.

 

[Dalwin]

While discussing districts and early growth on the home world, it is also worth noting that the slums give you a free point of population. You usually want to get to that one pretty early.