Whole lotta preachin’ going on. The last paragraph is about the stone.
Text Translation:
Of the adamas stone. Physiologus says: There is a stone called adamas found on a certain mountain in the east. Such is its nature, that you should search for it by night, not day, since it shines at night where it lies, but it does not shine by day, since the sun dulls its light. Against this stone, neither iron, fire or other stones can prevail. The prophet says of it: ‘I saw a man standing on a wall of adamant and in his hand was an adamant stone in the midst of the people of Israel’ (compare Amos, 7:7). But a creature cannot prevail against its creator, and for this reason Christ is the adamas stone. He stands on a wall of such stone, on the holy and living stones of which heavenly Jerusalem is built. These are the Apostles, the prophets and the martyrs, over whom neither fire, nor the sword nor the teeth of beasts could prevail.