also: じきん
noun
raw metal; unprocessed metal; ingot; bullion; ore
Refers to metal in its raw, unprocessed form, including ingots, bullion, or ore before refining or fabrication.
この工場では地金を加工して製品を作っている。
This factory processes raw metal to make products.
金の地金の価格が上がっている。
The price of gold bullion is rising.
noun
base metal (for plating)
Specifically the underlying metal onto which a plating or coating is applied; common in manufacturing and jewelry contexts.
この指輪の地金は銀で、表面に金メッキが施されている。
The base metal of this ring is silver, with gold plating on the surface.
noun
true character; true colors
Used figuratively to refer to a person's real nature, often with a negative connotation; frequently appears in expressions like 地金が出る (one's true colors show).
彼は普段は優しいが、怒ると地金が出る。
He is usually kind, but his true colors come out when he gets angry.
あの人の地金は意外とケチだ。
His true character is surprisingly stingy.
金属 is the general term for 'metal' as a material, while 地金 specifically refers to raw or base metal before processing or plating.
本性 means 'true nature' or 'innate character' and is more direct and neutral, whereas 地金 in the figurative sense often carries a negative nuance and is used in set phrases.
Compound of 地 (base, ground) and 金 (metal). The figurative sense derives from the idea of revealing the base metal beneath a surface coating.