Material of some medals

[matteti]

To our dear experts on the forum,
I was looking at the material (metal) used for the medals and found some contradictions between McDaniel book and Mondvor.narod.ru website. I know it's not of the highest importance, but I was curious to know more about this.

For Veteran of Labor and of Armed Forces:
- McDaniel says they are made of "an aluminium alloy"
- Mondvor says they are made of "silver-plated tombac"

For Strenghtening Military Cooperation:
- McDaniel says they are made of "an aluminium alloy"
- Mondvor says they are made of "golden color tombac"


Who is right and who is wrong?

Because after small research on the net, I found the definition of tombac:

An alloy of copper and zinc, resembling brass, and containing
about 84 per cent of copper; -- called also German, or
Dutch, brass. It is very malleable and ductile, and when
beaten into thin leaves is sometimes called Dutch metal.
The addition of arsenic makes white tombac

Nothing indicates any aluminium in the fabrication of tombac. And according to the definition of tombac, it seems possible to make it "white" or more silver by adding arsenic to the copper and zinc.

To make it more complicate, it seems that both BRASS and TOMBAC are made of copper and zinc... so, are they the same? or if not, I guess the proportion of each metal in the alloy is different.

If you know anything that can be useful to my learning, please just post it here. Thanks in advance.