terminal strips

I have a 7 position terminal strip block for joining wires.Typical black plastic cube that you see in many electric devices. It came out of a controller service box 240 v that stated on the outside that you should use only copper wires. But the metal in these terminals looks like alum and when I scratch the metal I dont see any copper color. The threads on the screws dont show any copper also. Do you think the metal is alum???
If so is it a bad thing to join 2 copper wires in one of the terminals if it is alum???There was only copper wires,6-10 gauge in this service box when it was in use and there wasnt any problems..what do you think??
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