Medallions-Generals of the Boer War

[Caratacus]

I am have a modest interest in the Boers/Huguenouts & recently saw several of these medallions apparently produced by the South African Mint- they look like silver.  Never seen these before and they do look interesting. There were some smaller ones of Cecil Rhodes,  Dr Livingstone & a few others I do not recognise (not Generals)

I feel daft asking but has any forum member bought these; are they silver and is there anything to watch out for?? 

Your thoughts and advice would be appreciated- thankyou