I figured out the mineral formula

[Yitzi]

The full mineral formula (for land squares without bases, boreholes, or forests) is as follows:
-The square is worth 0 if flat, 1 if rolling or rocky without a mine, and 2 if rocky with a mine.
-Add 2 if it has a mineral bonus, and add 1 if it has a relevant landmark (crater or volcano).
-If there is a mine, add another 1, plus 1 if it's rocky, 1 if it has a mineral bonus, and 1 if it's on a relevant landmark.  However, if there is no road then the total bonus from this cannot exceed the alphax entry marked "Limits mineral increase for mine without road in square".  The increase to base minerals for a rocky square without a mine (first step) is not affected by this limit.

[ete]

Cool, good work. This'll be good info to have on wiki and in the datalinks update.

[TarMinyatur]

-If there is a mine, add another 1, plus 1 if it's rocky, 1 if it has a mineral bonus, and 1 if it's on a relevant landmark.  However, if there is no road...

Hmm, I believe this should be:

-If there is a road, add another 1, plus 1 if it's rocky...

[Yitzi]

-If there is a mine, add another 1, plus 1 if it's rocky, 1 if it has a mineral bonus, and 1 if it's on a relevant landmark.  However, if there is no road...

Hmm, I believe this should be:

-If there is a road, add another 1, plus 1 if it's rocky...

No, it should not.  The "+1, plus another 1 if it's rocky" is dependent on the existence of a mine, though it is capped unless there is a road as well.  But even without a road, you still get 1 from that step (or more if alphax is set to more), so long as there's a mine.  Thanks for the proofreading anyway, though.

[Yitzi]

A correction to the formula: The last step, if there is a mine, adds +1 if there is a mineral resource bonus square or a relevant landmark, but does not add separately for both.  So, for instance, a mine+road on a rocky square with a mineral bonus on Mount Planet is worth 8: 2 for a rocky square with a mine, plus 2 for the mineral bonus and 1 for Mount Planet, plus 3 for the mine (1 base, 1 rocky, and 1 for the bonus), rather than 9.