What is the meaning of bluestone in calligraphy inscription?

Jinshi Qi is a broad, vigorous and simple expression style in China's traditional calligraphy. Gold is a tool, and stone is a tablet. Monuments have this stone-like feature. Judging from the ontology of calligraphy, this "stone spirit" is produced in this way. First, because the stone tablet itself, its stone quality determines its own hardness and endurance, which reflects the interest of knife carving; The second is the visual effect of rubbings.