In C:\...\EB\Data\world\maps\base\DESCR_REGIONS.TXT you'll find an entry for every province that contains the hidden resources, like this:

Adiabene
Arbela
romans_scipii
Kardouchoi
194 218 61
copper, river, persia, pahlavahome, EA, C, n1, n2, y4, n8
5
1