Onyx
Onyx is a banded variety of chalcedony. The colors of its bands range from white to almost every color (save some shades, such as purple or blue). Commonly, specimens of onyx contain bands of black and/or white.
Onyx is known to separate. It can help release negative emotions such as sorrow and grief. It is used to end unhappy or bothersome relationships.
source : crystal-cure.com