Q: Is a new altar supposed to have an altar stone?
A: An altar stone is a small piece of natural stone, roughly 12 to 14 inches square, inserted into the top slab of what the 1903 Catholic Encyclopedia rightly described as “the structure which answers the purpose of an altar when the whole altar is not consecrated.” Strange as it may seem, this small piece of stone was actually the entirety of the altar even when set into a larger altar-like setting. So in a proper understanding of terms, what is known in common parlance as an “altar stone” is simply a tiny altar. “Altar stone” and “portable altar” are exact synonyms.
A classification made in liturgical law before the Second Vatican Council distinguished between fixed altars and portable altars. Fixed altars were immovably attached to the floor and required a large, single piece of stone as its entire top slab, called the mensa. The “altar stone” or portable altar, as this latter name implies, could be carried from place to place. It was consecrated by a bishop, anointed in five places, incised with five crosses and given a tiny cavity, called the sepulcher, for the placing of relics. When this altar stone was set into a permanent structure made of other materials like wood or plaster, it was known as a “quasi-fixed” altar. Since liturgical law at the time only permitted altars made of stone, no matter how elaborate the “structure which serves the purpose of an altar” might be, if it was not made of stone, an altar stone had to be set into it to serve as the altar proper. Though the mind of the Church clearly preferred that the principal altar in a church be fixed with a full-sized stone mensa, permissions were given for a quasi-fixed altar if a large piece of stone was not available. And as with many permissions given by way of exception, it became almost the norm in American churches that even principal or “high” altars had only a 12-inch stone serving as their actual altar. Rightly, liturgical scholars urged that the full sign of the altar be expressed whenever possible with a full stone mensa, and encouraged people to avoid quasi-fixed altars which gave the appearance of a full altar while actually reducing it the minimum size needed to hold a chalice and paten.
Postconciliar legislation remedied this problem by allowing movable altars to be constructed of “any noble and solid materials suited to liturgical use” (General Instruction of the Roman Missal, 301). While the Church’s liturgical books maintain a clear preference for a fixed, stone altar, nonetheless a moveable altar can be made completely of wood, for instance, with no need for a stone insert. While not forbidden by name, altar stones are no longer prescribed by liturgical legislation, and therefore it is safe to conclude that the quasi-fixed arrangement is not envisioned for new altars.
In one last point of clarification, an older fixed altar with a stone mensa may show a small square cut out of the same stone near its center. This is not an altar stone, but rather the covering of the cavity in the mensa itself in which relics were placed. Depositing of relics within the mensa was a permitted option among others, including placing relics under the altar, until the postconciliar Order of the Dedication of an Altar (ODA) specifically forbade it in 1970 (par. 11). Ironically, the preconciliar rules for the construction of an altar required that the mensa be made of one piece of stone, noting that if it accidentally cracked into two pieces, it lost its consecration. Yet the very same rubrics allowed the mensa to be cut into two pieces to carve out a place for relics. Today’s law requires relics to be placed under the mensa rather than within it precisely to remedy this situation, and therefore the altar is to be fully itself without attenuation, becoming clearly recognizable as Christ, the “living Altar of the heavenly Temple” (ODA, 1).
—Answered by Dr. Denis McNamara,
Executive Director of the Center for Beauty and Culture at Benedictine College