Re-purposing altar stones

In Paul Turner's Blog by Paul Turner

Q: We spoke briefly at a conference about re-purposing old altar stones in new altars (in short, OK within the altar’s support, but not embedded in the mensa). The Order for Blessing a [non-fixed] Altar makes no mention of relics in these altars, and you write, “A fixed altar may include relics of saints; a movable altar may not” (“New Church, New Altar“ p. 145). Does the Order explicitly state this prohibition? If so, where; if not, is this an argument ex silencio? I’m not challenging you, or even disagreeing, but need advice how to approach a situation in my own diocese. 

Here, a couple young priests lamenting the mothballing of old altar stones have designed their own private, temporary altars to celebrate Mass up at their cabins on days off. They built these altars with altar stones embedded in the surface of the Mensa, without consulting me. Further, they asked the bishop to bless their temporary altars, which he did (!).

How should I address these priests and bishop—or should I? Any insight you have would be appreciated. 

Fraternally, 

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A: Nice to hear from you. 

I should have put a reference there. In The Order of the Dedication of a Church and an Altar, Chapter VI, The Order of Blessing an Altar, one fines this, “It is not permissible to place the relics of Saints in the base of a movable altar” (3).
The situation you describe is quite common, from what I understand. I think it would benefit people to know what the church teaches.