Chrism (Greek χρίσμα, meaning "ointment") is consecrated oil used during the administration of certain mysteries, particularly those of baptism and anointing of the sick (unction), and other rites of the Orthodox Church. Chrism is sometime referred to as myrrh (from the Greek μύρων), holy oil, or consecrated oil.
The use of an oil in Christian ceremonies is mentioned in many early Christian documents including writings by Theophilus and Tertullian. Cyril of Jerusalem details the practices of using oil or ointment that is “symbolically applied to the forehead, and other organs of sense.” He further notes that the “ointment is the seal of the covenants” of baptism and God’s promises to the believer. He taught that being "anointed with the oil of God” was a sign of a Christian (Christos meaning “anointed”), and a physical representation of receiving the Gift of the Holy Spirit.
In Orthodox Christianity, chrism is a prominent part of the baptismal rite in which, under normal circumstances, the newly enlightened (including infants) is anointed with chrism in the mystery of chrismation. Chrism is used also during the consecration of churches in which the altar table and walls are anointed.
Chrism is a mixture of olive oil and aromatic essences following the pattern of the preparation of anointing oil described in Exodus 30:22-33. Chrism is prepared when needed during Holy Week. The preparation rite begins on Holy Monday and ends with the Divine Liturgy on Holy Thursday when the new chrism is carried in during the Great Entrance and placed upon the altar table. The chrism is prepared by the ruling bishop of each autocephalous church, assisted by members of the Holy Synod. After its preparation the chrism is distributed to the bishops, who in turn pass it to the parishes where it is needed.
In the Patriarchate of Constantinople, for example, Chrism is manufactured roughly every ten years. It is produced from 57 ingredients, including the ash from burnt ikons.