Information about Chioniades survives from some contemporary sources. In 1347,
George Chrysokokkes wrote that He was born in Constantinople, probably around 1240, and was originally named George. Sixteen of Chioniades' letters have survived, which confirm that he received assistance from Alexios II and traveled to Persia. Chioniades translated a number of
Arabic and
Persian works on
mathematics and
astronomy, including the astronomical tables of his teacher
Shams al-Din al-Bukhari, who had worked at the famous
Maragheh observatory under the polymath
Nasir al-Din al-Tusi. Chioniades played an important role in transmitting several innovations from the Islamic world to Europe. These include the introduction of the universal latitude-independent
astrolabe to Europe and a Greek description of the
Tusi couple, which would later have an influence on
Copernican heliocentrism. Chioniades also translated several
Zij treatises into Greek, including the Persian
Zij-i Ilkhani by al-Tusi and the Maragheh observatory as well as the Seljuk
Sanjaric Tables by
al-Khazini, an Islamic astronomer of Byzantine Greek descent. Chioniades resided in Tabriz, at the time the Mongol capital, from 1295 to 1296, serving as the Orthodox bishop to the Orthodox community in that city, and later returned to Constantinople. In 1302 he returned to Tabriz as bishop. According to David Pingree, this may have been in connection with
Andronikos II Palaiologos's attempt to form an alliance with
Ghazan Khan in the summer of 1302. He stayed at Tabriz at least until 1310, before returning to Trebizond, where he is attested as a
hieromonk around 1315. Chioniades also wrote religious works, including a commentary on
John of Damascus, a liturgy on St. Eugenios of Trebizond, and a profession of faith. ==Notes==