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
"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
The Sarcophagi of Helena and Constantina are two fourth century porphyry sarcophagi located in the Pio-Clementine Vatican Museum in Rome.
Porphyry (geology)
…fragments are at the Archaeological Museum in Split, Croatia. The oldest and best-preserved ones are now conserved at the Vatican Museums and known as the Sarcophagi of Helena and Constantina. Nine other imperial porphyry sarcophagi were long held in the Church of the Holy Apostles in Constantinople. They were described by Constantine VII…
Sarcophagus of Helena
Sarcophagus of Constantina (340 AD)