Metal , the fourth phase of the Chinese philosophy of Wu Xing, is the decline of the matter, or the matter's decline stage. Metal is yin in character, its motion is inwards and its energy is contracting. It is associated with the Autumn, the west, old age, the planet Venus, the color white, dry weather, and the White Tiger (Bai Hu) in Four Symbols. The archetypal metals are silver and gold.