Galena and bauxite, for two (4)
I believe the answer is:
ores
'galena and bauxite for two' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for ores that I've seen before include "Metal-bearing minerals" , "Bauxite, haematite etc" , "Sources of metal" , "Mineral deposits" , "Rocks or minerals containing metals" .)