Can the Iron Drawves use the scepter of avarice?
In the rulebook in french, under Scepter of Avarice it says: "Dwarves do not like being accused of avarice".
Yes, they can use it. The conflict comes with the Mine of the Lost Dwarves, not the Iron Dwarves. In english:
The Scepter of Avarice
At the end of his turn, before scoring, the player who controls the Scepter of Avarice places it in a Region his troops occupy to double the number of Victory coins collected from that Region. Dwarves don't like to be known as greedy and will not accept the Scepter of Avarice in their mine though: The Scepter will have no effect if placed in a Region containing the Mine of the Lost Dwarf. Note that the Scepter never doubles the number of Victory coins received from other players (e.g. Liches, Thieving and Froggy’s Ring powers).
The Mine of the Lost Dwarf
At the end of his turn, the player whose troops occupy the Mine of the Lost Dwarf's Region collects 2 bonus Victory coins. The Mine of the Lost Dwarf yields these bonus coins even if the Troops that occupy its Region are In Decline. The Scepter of Avarice has no effect, if placed in the Mine.