Whether at the Chrism Mass or other diocesan liturgical events, the unity of faith is expressed in the coming together of the Bishop, the presbyterate and the lay faithful. This citation from the Constitution on the Sacred Liturgy (Sacrosanctum Concilium) aids in understanding significant diocesan events:
“The bishop is to be considered the high priest of his flock from whom the life of his people in Christ is in some way derived and on whom it in some way depends. Therefore, all should hold in the greatest esteem the liturgical life of the diocese centered around the bishop, especially in his cathedral church. They must be convinced that the principal manifestation of the Church consists in the full, active participation of all God’s holy people in the same liturgical celebrations, especially in the same Eucharist, in one prayer, at one altar, at which the bishop presides, surrounded by his college of priests and by his ministers” (SC, n. 41).
Olea sancta – Sacred Oils
The Church makes use of three holy oils: the Oil of the Sick, the Oil of Catechumens, and the Holy Chrism oil. The first two are blessed, and the bishop consecrates the third. The Oil of the Sick (Lat. Oleum Infirmorum): The oil of the sick, which is pure olive oil, is used for the Sacrament of the Anointing of the Sick. The priest lays hands on the sick or elderly person, says special prayers and anoints the person by placing the sacred oil in the form of a cross on the forehead and hands. Through this sacrament, God gives the sick person grace and strength to bear the illness or infirmity. In addition, many Catholics have witnessed the power of this anointing to bring spiritual, emotional, and even physical healing.
The Oil of Catechumens (Lat. Oleum Sanctum or Oleum Catechumenorum) : Both adults and infants prior to baptism are anointed with the oil of the catechumens, which is also pure olive oil. For adults who have not been baptized and preparing to do so on Easter, this pre-baptismal anointing often takes place during a special liturgical rite when the person begins to prepare for the Sacrament of Baptism. At the beginning of the process known as the Rite of Christian Initiation for Adults (RCIA), each person preparing for initiation is anointed with the Oil of the Catechumens. For an unbaptized adult, this rite most often takes place during Mass, prior to holy Communion. The priest or deacon anoints the catechumens. Then he prays that God will instill them with wisdom for discernment and with the strength necessary to avoid evil during their inquiry into the Catholic faith and their preparation for a life with Christ. In a similar way, an infant brought to the font is anointed just before being washed clean of sin through the sanctifying waters of baptism. This anointing is to help the child ward off evil, avoid temptation and possess the faith necessary to carry the cross of Christ throughout life.
Holy Chrism (Sanctum Chrisma) is olive oil mixed with balsam. The oil symbolizes strength, whereas the fragrant balsam represents the “aroma of Christ” (2 Cor 2:15). Anointing with chrism signifies the gift of the Holy Spirit. It is used to consecrate someone or something to God’s service. Each year the bishop uses Holy Chrism when young people are confirmed, and both he and priests use chrism at the Easter Vigil when adults are confirmed after baptism. The bishop traces the Sign of the Cross with chrism on the forehead of the one being confirmed and says, “[Name], be sealed with the gift of the Holy Spirit.” Chrism is also part of the baptismal rite. Following an infant’s baptism with water and before the child is clothed with a white garment, the cross with chrism is traced on the crown of the child’s head, marking him as a Christian. Holy Chrism is also used during the ordination of a priest (the Sacrament of Holy Orders) and the consecration of a bishop. Chrism, too, is the anointing used in the consecration of a church and the blessing of an altar and the vessels used at Mass.
Mass of the Holy Chrism: Each year the local bishop blesses enough new oils for every parish during this annual Mass. The holy oils are then either taken from the cathedral by designated individuals or transported to parishes, where they are available for use during that year. Though the bishop cannot be physically present at every baptism or confirmation in his diocese, he is symbolically present through the holy oils he blesses.
Order of Worship at Chrism Mass: After the Liturgy of the Word, the blessing of the oils takes place. In a formal procession, olive oil is brought forward in special urns; the Oil of the Sick is presented first, next the Oil of Catechumens, and finally oil for the Holy Chrism. The bishop prays over and blesses each oil individually. The ritual for creating and consecrating the Holy Chrism is different from the other two oils. To confect Holy Chrism, the bishop mixes oil from the balsam plant with the olive oil, breathes on the mixed oil to signify the presence of the Holy Spirit, and then says a prayer to consecrate it. Once blessed in this way, the chrism and the other oils are no longer ordinary ointments. Instead, they are a holy, precious gift from God to the Church, signifying cleansing and strengthening, healing and comfort, and the life-giving grace of the Holy Spirit.
Excerpted from D.D. Emmons. http://www.simplycatholic.com/what-are-holy-oils
Nature and dignity 