Na Yin Metal in the Sea (海中金): the image of a pillar pair
Na Yin: Metal in the Sea (海中金)
Na Yin assigns a poetic image to each consecutive pair of stem-branch combinations. "Metal in the Sea" (Hai Zhong Jin) belongs to the pairs 甲子 and 乙丑.
How Na Yin is used
Traditional readers use Na Yin as a texture layer — an image for the quality of a pillar pair — rather than as a prediction. Different schools weight it differently.
Where you can see it
Build a chart on MingLens to see the Na Yin of your year pillar and check whether "Metal in the Sea" appears in your structure.
Boundary
Na Yin images are cultural vocabulary, not statements of fact about a person.