Porphyry
International Standard Bible Encyclopedia · James Orr and contributors
por'-fi-ri (in Es 1:6, the Revised Version margin has "porphyry" (the King James Version margin "porphyre") for bahaT, English Versions of the Bible "red (marble)"; the Septuagint has smaragdtes, which was a green stone): Porphyry is an igneous rock containing distinct crystals of feldspar in a feldspathic matrix. It may be purple or of other colors, as green. "Porphyry" is from porphureos, "purple."
Source of the article
International Standard Bible Encyclopedia — James Orr, general editor and contributors; CrossWire SWORD module ISBE 2.2
Bible Strong digital edition from CrossWire module 2.2; historical scholarship originally published in 1915