Architectural Geology of Byzantine Constantinople, Part 7: Ophicalcite and Marble | Hagia Sophia, Istanbul, Turkey (537 AD; repairs and additions in succeeding centuries)
This stretch of the upper-level gallery may not be one of the most photogenic spots in Hagia Sophia, but it shows the state of stone and mosaic conservation in 1976. And, more important, it's a one-frame mini-encyclopedia of this great structure's most widely used rock types.
At left, forming the row of columns overlooking the naos, are shafts of medium-green Larissa Ophicalcite, Jurassic to Cretaceous in age and quarried in Thessaly. This breccia, a favorite of sixth-century Byzantine architects, contains large angular clasts of dark-green serpentinite—chemically altered rock from the Earth's mantle—and white marble haloed with the mint-green mineral serpentine.
Inboard and to right stand two stouter columns. Both their shafts and basket capitals were fashioned from the Constantinople region's own premium building material, Proconnesian Marble extracted from the island of Marmara in the Sea of the same name. This major quarrying operation was sited a short sail from the imperial capital.
The Proconnesian began as a Precambrian to Lower Paleozoic limestone protolith that was metamorphosed in the Permian period, at the time of the assembly of Pangaea. Here it's also present in the lower rows of cladding on the pier at center. These panels are fine examples of the veined variety of this famous stone selection. Its darker zones are composed of the mineral graphite derived from organic remains; the lighter are predominantly calcite.
Above the wide plastered zone is a band of bookmatched Iasian Marble. Taken in ancient and Early Byzantine times from Iasos in the Asia-Minor province of Caria, this highly folded marble has been known to Renaissance Italian stonemasons and everyone else since as "Cipollino Rosso." This is a reference to its layered appearance, supposedly reminiscent of a cut onion.
As my previous two photos in this set demonstrate, the Iasian is often a dramatic interplay of gray graphite, white calcite, and blood-red hematite. In this spot, however, its coloration looks rather blah and not at all sanguine. Is this a sign that it needed a good cleaning? Or is it just an artifact of my old slide's own fading?
To see the other photos and descriptions of this series, visit my
Architectural Geology of Byzantine Constantinople, Part 7: Ophicalcite and Marble | Hagia Sophia, Istanbul, Turkey (537 AD; repairs and additions in succeeding centuries)
This stretch of the upper-level gallery may not be one of the most photogenic spots in Hagia Sophia, but it shows the state of stone and mosaic conservation in 1976. And, more important, it's a one-frame mini-encyclopedia of this great structure's most widely used rock types.
At left, forming the row of columns overlooking the naos, are shafts of medium-green Larissa Ophicalcite, Jurassic to Cretaceous in age and quarried in Thessaly. This breccia, a favorite of sixth-century Byzantine architects, contains large angular clasts of dark-green serpentinite—chemically altered rock from the Earth's mantle—and white marble haloed with the mint-green mineral serpentine.
Inboard and to right stand two stouter columns. Both their shafts and basket capitals were fashioned from the Constantinople region's own premium building material, Proconnesian Marble extracted from the island of Marmara in the Sea of the same name. This major quarrying operation was sited a short sail from the imperial capital.
The Proconnesian began as a Precambrian to Lower Paleozoic limestone protolith that was metamorphosed in the Permian period, at the time of the assembly of Pangaea. Here it's also present in the lower rows of cladding on the pier at center. These panels are fine examples of the veined variety of this famous stone selection. Its darker zones are composed of the mineral graphite derived from organic remains; the lighter are predominantly calcite.
Above the wide plastered zone is a band of bookmatched Iasian Marble. Taken in ancient and Early Byzantine times from Iasos in the Asia-Minor province of Caria, this highly folded marble has been known to Renaissance Italian stonemasons and everyone else since as "Cipollino Rosso." This is a reference to its layered appearance, supposedly reminiscent of a cut onion.
As my previous two photos in this set demonstrate, the Iasian is often a dramatic interplay of gray graphite, white calcite, and blood-red hematite. In this spot, however, its coloration looks rather blah and not at all sanguine. Is this a sign that it needed a good cleaning? Or is it just an artifact of my old slide's own fading?
To see the other photos and descriptions of this series, visit my