What is the black pigment in the murals of the four gods' clouds and gas maps?

The black pigment of the murals of the Four Gods Clouds and Gas Maps is a mineral pigment.

The black pigment commonly used in China traditional painting is carbon black or rock black. However, after research, it is found that the black used in the four gods cloud is not this kind, but an ink color mixed by vermilion and malachite green in proportion.

This shows that the ancients have mastered the color matching method in painting. This different proportion of color matching produces different colors and different textures in the picture, which makes the color more stable. This combination of strong contrast tones of red and black makes the whole picture present a harmonious and unified warm tone, plus a small amount of cold tone collocation, which makes the color more abundant.