This would be good, could also be incorporated not just to the parent city but globally to all cities for Chichen Itza, however I'm against creating "must have" wonders. But let me offer an alternative: With a certain mid- to late-game tech/civic, rainforest (or extended to every tile that is affected by a negative appeal hit) tiles generate +1 science for every -1 (or-2 if that works better for balancing) appeal hit to that tile. Maybe +1 science for every -1/-3/-5 etc appeal hit and +1 production for every -2/-4/-6 etc appeal hit. The reasoning is that faith generation has become more and more potent as the game has developed, and the benefits of having lush global appeal has also become more and more potent. While this is a good teaching tool for kids, there should be a way of playing the game where throwing caution to the wind in terms of environmentalism could unleash an alternate approach that generates an industrial powerhouse. It also addresses my personal qualm that mines are horrible now - this is somewhat tangential so I'll let you skip it if you want.On a minor note, it somewhat annoys me that other than brazil, you always chop rainforest then replant woods for the appeal boost. Perhaps after a certain mid to late game tech/civic, they stop being negative appeal and act like woods.
Spoiler why mines are horrible :
First and foremost, output: mines provide one more production and a second production very early on with apprenticeship, and eventually an extra 2 with more advanced technologies. There's the bit about Ruhr Valley, but that only affects the mines of a single city and requires the investment of an industrial era wonder. In contrast, a lumber mill provides +2 production upon unlocking, making classical era lumber mills give as much of a bonus as medieval era mines, and also can make 2 more production with more advanced technologies, so both improvements eventually reach their potential of +4 production, however, the lumber mill is equal or ahead for most of the game except for the timeframe of when you have industrialization but not steel. EXCEPT, having a lumber mill implies that there is a woods on the tile which is +1 production, meaning that the total yield of the tile will always be better, but just equal during that short window, albeit at the expense of a chop. Second, availability: mines can only be on hills and minable resources, which early on is more frequent than woods. But you eventually earn the ability to plant woods, whereas you never gain the ability to "raise hills." Finallly, mines always add a negative appeal hit, which can add up with clusters of mines, whereas lumber mills not only don't hurt appeal but inherently add to it (for woods not rainforest) as the tile has woods which adds to appeal and later adds a second for woods that were there from the beginning.