金 jīn is a pictograph of gold nuggets beneath the earth. The upper element resembles a person or roof 人/亼; the lower element 土 represents earth; the two small strokes on either side of the lower body represent gold nuggets embedded in the ground. The whole image: precious ore found within the earth — not mined yet, but there.

The character originally meant "gold" specifically, then broadened to mean "metal" in general (金属 jīnshǔ), and then by extension "money" (金钱, 现金). This semantic drift follows the logic of value: gold → the most valuable metal → valuable metals generally → money (the stored form of value).

金 is also one of the most productive radicals in Chinese — almost every metal and many alloys have the 金 radical: 银 yín (silver), 铜 tóng (copper), 铁 tiě (iron), 铝 lǚ (aluminum), 钢 gāng (steel), 钱 qián (money — originally copper coins). The periodic table of elements in Chinese uses 金 for all metals: 钙 gài (calcium), 锂 lǐ (lithium), 钠 nà (sodium).

In the Wu Xing 五行 system, 金 Metal is associated with: the direction West (西) · the season Autumn (秋) · the quality sharpness and precision · the organ Lungs (肺) · the color White (白) · the planet Venus (金星 jīnxīng — "gold star").

The planetary name is important: 金星 is Venus, 火星 is Mars, 木星 is Jupiter, 水星 is Mercury, 土星 is Saturn — all named for their corresponding Five Phase element. The names encode the entire cosmological system.

In the productive cycle (相生 xiāngshēng): Earth produces Metal (土生金) — ore is found in the earth. In the controlling cycle (相克 xiāngkè): Metal controls Wood (金克木) — an axe cuts a tree. Metal yields to Fire (火克金) — fire melts metal.