Porphyry
Porphyry is a very hard red or purple rock which was in the ancient world quarried only in Egypt and was reserved for the use of the Pharaoh.In Byzance the childbirth's room of the royal family was called the purple.
Louis XIV King of France had the largest collection by acquiring the BorghÃÂèse collection.
Porphyry (born about 233 C.E., 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.
His most famous book is about Pythagoras, named Vita Pythagorae or Life of Pythagoras (which is not to be confused with the book with the same name by Iamblichus).