Porphyry

Porphyry is a very hard red or purple rock which was in the ancient world quarried only in Egypt and was reserved to the use of the Pharaoh.

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Porphyry (born about A.D. 233, died around 305) was born Malchus in Syria, and was given his Greek name by his teacher Longinus at Athens. Porphyry later became a follower of the neo-platonism of Plotinus, of whom he wrote a biography. He was an opponent of Christianity and wrote a book against it which has not survived. He wrote widely on religion and philosophy, including musical theory.