How is discovery probability calculated?

[Optimizer]

Does anyone know how the game calculates the chance of finding a mineral resource when building a mine?

In CIV4ImprovementInfos.xml there is a tag <iDiscoverRand>10000</iDiscoverRand> - but what does "10000" mean? In other words - shall I increase or decrease the value if I want greater chance to find resources?

 

[Thalassicus]

It's probably a denominator. So every turn every mine would have a 1/10,000 chance of discovering a new resource. Increasing it would increase the time it takes between discoveries, and vice versa.