Rich vein (4)
'rich vein' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for seam that I've seen before include "Underground layer of mineral" , "Unfasten" , "The line where two edges are stitched together" , "Joint between two edges" , "Stratum (of a mineral)" .)
'rich vein' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for lode that I've seen before include "Deposit of valuable ore found in surrounding rocks" , "Rich source" , "A deposit of ore, say gold" , "Vein of metallic ore sounds heavy" , "Mineral vein" .)