Jet Stone has been used historically as a mourning stone, and to ease depression and grief. It�s been used as well for protection from, and removal of, negative energies.
Howlite is known as a stone of attunement. It is said to help the wearer become aware, to receive wisdom, to calm upset emotions, and to be oneself. It is also said to help rid oneself of negative character traits, such as selfishness, rudeness, and greed.