Method of carrying almost half a ton, including rare minerals (8,4)
I believe the answer is:
firemans lift
'method of carrying' is the definition.
'almost half a ton including rare minerals' is the wordplay.
'almost' means to remove the last letter (most of the word but not all of it).
'half a ton' becomes 'fifty' ('ton' can mean a hundred).
'including' is an insertion indicator.
'rare' is an anagram indicator.
'fifty' with its last letter removed is 'fift'.
'minerals' with letters rearranged gives 'remansli'.
'fift' going around 'remansli' is 'FIREMANS LIFT'.
(Other definitions for firemans lift that I've seen before include "Method of rescuing from a conflagration" , "Over-the-shoulder carrying technique" , "rescue manoeuvre" .)