The Portrait of the Four Tetrarchs is a porphyry sculpture group of four Roman emperors dating from around 300 AD. The sculptural group has been fixed to a corner of the façade of St Mark's Basilica i
Portraits of the Four Tetrarchs, porphyry, c. 305 A.D., embedded in the façade of St. Mark's Basilica, Venice
Portrait of the Four Tetrarchs (head and torso detail-group of four)
Missing heel portion kept in the Istanbul Archaeology Museum
Detail
Porphyry (geology)
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Porphyry is any of various granites or igneous rocks with coarse-grained crystals such as feldspar or quartz dispersed in a fine-grained silicate-rich, generally aphanitic matrix or groundmass. In its
Portrait of the Four Tetrarchs
…The Portrait of the Four Tetrarchs is a porphyry sculpture group of four Roman emperors dating from around 300 AD. The sculptural group has been fixed to a corner of the façade of St Mark's Basilica…
"Imperial Porphyry" from the Red Sea Mountains of Egypt
A waterworn cobble of porphyry
Rhyolite porphyry from Colorado; scale bar in lower left is 1 cm (0.39 in)
Igneous porphyry from the Hunter Mountain pluton in the Last Chance Range in Death Valley National Park