This kanji depicts a blackened vessel or bag filled with soot from a fire. Therefore, this kanji came to mean the color ‘black’.
black(黒)
silent(黙)
This kanji consists of two parts: the ‘black’ radical on the left (representing a vessel filled with soot) and the ‘dog’ radical on the right. It depicts a dog staying quiet in the dark, and therefore came to mean ‘to be silent’ or ‘to keep quiet.’