Crimson & Teal & Cobalt

Crimson is the terracotta — the deep vivid crimson of the Iranian terracotta brick that forms the structural substrate of the most celebrated examples of Safavid Islamic architecture. Iranian terracotta: the specific deep red-to-crimson color of the fired clay bricks used in Iranian architecture since the Elamite period (approximately 2700-539 BCE) — produced by the iron oxide (Fe₂O₃ — hematite — red iron oxide) content of the local Khuzestani and Isfahani clays, which produces a distinctive deep crimson-to-rust-red when fired at approximately 900-1100°C in an oxidizing atmosphere. The Safavid bricklayers of Isfahan (16th-17th century CE) used the deep crimson terracotta brick as both a structural and an aesthetic material — the exposed terracotta of the arches, squinches, and vaults of the Sheikh Lotfollah Mosque's interior creates a specific warm crimson-to-rust backdrop against which the brilliant tilework appears most dramatically jewel-like. Teal is the turquoise tile — the dark vivid teal of the Iranian architectural turquoise tile (firouzeh — فیروزه — turquoise — also: kashi-ye firouzeh — the turquoise tile, from kashi — tile — and the city of Kashan, one of the most important Iranian ceramic centers). The firouzeh color: the specific dark vivid teal-to-turquoise of Iranian architectural tiles is produced by copper oxide (CuO — the most important colorant in all Iranian and Islamic tile glazes since at least the 9th century CE) added to a lead- or tin-based transparent glaze. The specific teal tone of the most characteristic Iranian firouzeh tiles (not pure blue-green, but a slightly darker, more vivid teal — specifically the color that approximates the hue of the finest Iranian turquoise stones, which come from the Nishapur (Neyshabur) mines in Khorasan, Iran — the most important turquoise-producing region in the world for at least 2,000 years, with turquoise deposits exploited since approximately 2000 BCE). Cobalt is the cobalt tile — the deep saturated cobalt of the lapis-blue and cobalt-blue tile elements in Iranian Islamic architecture. Cobalt-blue glaze (lazur — لازور — Arabic and Persian: from lāzhward — lapis lazuli — the most important historical blue colorant before synthetic cobalt blue) was produced by adding cobalt-containing minerals (cobaltite — CoAsS; or smalti — cobalt glass from Saxony or Bohemia, exported to Iran and Turkey as 'cobalt blue') to tin-opacified lead glazes. The cobalt-blue tiles in Safavid architecture complement the turquoise-teal tiles in a complex polychromatic scheme — the combination of turquoise-teal (firouzeh), cobalt-blue (lazuri), white (safid — from tin-opacified glaze), black (from manganese — manganez), and gold-to-yellow (from lead-antimonate pigment — Naples yellow) creates the full color vocabulary of Safavid tilework. The Sheikh Lotfollah Mosque: built by the order of Shah Abbas I (Abbas the Great — 1571-1629 CE, the most powerful and most artistically sophisticated Safavid Shah, who moved the imperial capital to Isfahan in 1598 and initiated the construction of the Naghsh-e Jahan — 'Image of the World' — Square complex) and dedicated to his father-in-law, the Lebanese Shi'a scholar Sheikh Lotfollah Meyssi al-Ameli. The mosque's most celebrated feature: the interior dome — a single dome approximately 20 meters in diameter, decorated with a spiraling arabesque pattern of turquoise-teal, cobalt-blue, white, black, and gold tilework that converges at the oculus (the central opening at the apex of the dome) in a sunburst pattern — widely considered the most extraordinarily beautiful single architectural surface in the world.