[Alneyan]

My trusted calculator eventually stumbled on the correct order. The basic formula should be as follow:

(Extraction Facility value) x (planet’s resource type %) + [(empire’s racial %) x (planet’s happiness %) x (population %)] = total mineral resources committed to your empire for that facility.

Planetary values alone multiply with basic production, and all the rest adds together. I do not know what role the special facilities have however.