What does the word Xin belong to in the five elements?

The word Xin is composed of three golds, so the five elements belong to gold.

The Five Elements is a systematic view of China's ancient philosophy, which is widely used in traditional Chinese medicine, geomantic omen, numerology, physiognomy and divination. The meaning of the five elements includes five basic trends in the evolution of Yin and Yang: water (for infiltration), fire (for disillusionment), gold (for convergence), wood (for growth) and earth (for integration).

Ancient philosophers in China used the theory of five elements to explain the formation of all things in the world and their relationships. It emphasizes the whole and aims to describe the movement form and transformation relationship of things. Yin and Yang are ancient theories of unity of opposites, and the five elements are primitive system theories.