The word chrism derives from the Greek word for ointment. Chrism is oil, generally olive oil, which has been scented with spices (generally myrrh and/or balsam, sometimes frankincense) and blessed by the bishop for use in Baptism. When a person is baptized, after receiving Baptism with water and in the Name of the Father, and of the Son, and of the Holy Spirit, the priest then uses his/her thumb to make the sign of the cross on the person’s forehead with chrism, saying “... you are sealed by the Holy Spirit in Baptism and marked as Christ’ own forever. Amen.” (This prayer is found at p. 308 in the prayer book.) The use of myrrh in particular recalls the baptismal references to dying to one’s self, to be reborn with Christ; of dying with Jesus to share in His resurrection.
Two other holy oils are also used. They are essentially the same as chrism, but are used for different purposes. The first is oil for anointing, which is used in anointing and praying for the sick and dying (as specified in James ch. 5, and in many early Church documents). Anointing of the sick or dying is referred to as “unction”. The sick are generally anointed on the forehead; the dying on head plus both hands and both feet.
The second is oil for anointing of catechumens (persons who are members of the Church who are seeking Baptism). Catechumens may not receive Communion; only Baptized persons can. Therefore, the oil of catechumens is provided for their anointing while they are being instructed for Baptism. The oil of catechumens is also considered to be an oil of consecration (that a person is set-aside for Christ). At the coronation of a British monarch (who is also the head of the Church of England) the Archbishop of Canterbury anoints the sovereign on hands, head and heart in a ceremony considered the height of the coronation, and shielded from public view by the “canopy of state”.
Chrism and holy oils may only be consecrated by a bishop. This happens once a year at the Chrism Mass, at which the clergy of the diocese gather with the bishop. This happens during Holy Week.
Holy oils are kept in an “oil stock,” which is a small metal cylinder with a screw-on top. The cylinder is filled with cotton wool soaked in the oil. An oil stock may be a “triple oil stock,” which has three cylinders that screw one on top of each other. Each oil stock is marked for what is contains. Chrism is marked “OC” (from the Latin oilium chrismatorum, oil of chrismation). Oil for the anointing of the sick is marked “OI” (Latin = oilium infermorum, “oil of the sick”), and the oil of catechumens is marked “SC” (Latin = sanctum chrisma, “holy ointment”).