gold
鉚 centers on gold as a precious metal. The meaning is narrow and concrete, referring to the material itself.
鉚 combines 金 (metal, gold) with 卯, which likely contributes the sound リュ. The character is a phono-semantic compound for gold.
The left side 金 is metal, and the right side 卯 looks like a pair of doors. Imagine a vault with golden doors: 鉚 is gold.
For リュ, picture a golden lyre (リュ) made of pure gold. The lyre's sound cues リュ while the gold shines.