"Chrism" is the name of an oil used sacramentally, a mixture of olive oil and an aromatic resin called balsam. The Scriptures and tradition are full of references to oil, to its uses in cleansing, healing, and anointing.
At the annual Chrism Mass, before Holy Week begins, the archbishop gathers with the priests of the archdiocese and celebrates Mass, manifesting the unity of the priests with their archbishop. During this liturgy the archbishop blesses three oils:
the oil of catechumens ( oleum catechumenorum or oleum sanctorum);
the oil of the infirm ( oleum infirmorum),
holy chrism ( sacrum chrisma).
These oils will be used in the administration of the sacraments throughout the archdiocese for the coming year.