* Hardness and impenetrability: Stones can also represent hardness and impenetrability. In literature, characters who are difficult to reach or understand may be described as being "stone-faced" or having a "heart of stone."
* Coldness and indifference: Stones can also be seen as cold and indifferent. In literature, characters who are unfeeling or apathetic may be described as being "cold as stone" or having a "heart of stone."
* Silence and secrecy: Stones can also represent silence and secrecy. In literature, characters who are keeping secrets or who are unwilling to speak may be described as being "silent as a stone" or having a "heart of stone."
* Eternity and timelessness: Stones can also represent eternity and timelessness. In literature, characters who are immortal or who have a long history may be described as being "as old as the stones" or having a "heart of stone."
* Wisdom and knowledge: Stones can also represent wisdom and knowledge. In literature, characters who are wise and learned may be described as being "full of wisdom" or having a "head full of stones."