Co₂Fe₆O₁₆Sb₂Zn₂

Architectural potential

A cobalt-antimony-zinc-iron oxide tuned for the load-bearing fired-ceramic register — pushed toward the higher-strength end of the family, offering block-work, structural tile, and compressive vaulting candidate geometry. At 100 MPa the body sits squarely in the descendant-of-structural-brick register: vault voussoirs, pier-block infills, structural-tile cladding on load-bearing walls, and fire-resistance-critical elements in institutional architecture. Natural placements are compressive-vault blocks in experimental workshop buildings, structural-tile cladding over CLT columns in fire-regulated programmes, pier-block units in pavilion architecture where the saturated cobalt-blue body is part of the argument, and hearth or flue-lining elements in kitchen and fireplace construction. The five-kilogram workshop ceiling makes full-block specification feasible without specialist scaling. The environmental caveat is the dominant one: embodied CO₂ runs 3.5 times a fired clay brick and firing energy runs 75 per cent higher, so any bulk specification has to pay the carbon bill with the cobalt-blue register and the fire-resistance argument together. The supply-chain score at zero is the other caveat: cobalt and antimony procurement sits inside ethically fraught extractive chains with deep human-rights concerns, and specification demands verified sourcing before the first block is fired.

Material character

The 120×120×128 mm block reads a saturated deep cobalt-blue driven by the Co²⁺ chromophore, with faint green-black shadow angles where the iron-oxide matrix cools the hue. Surface vitrified-matte from the 1100 °C fire, with the typical fired-ceramic skin — fine-grained, slightly glassy at grazing light where the antimony flux has approached partial melt. Edges cold-cut, kerf-whitened, showing the transition from the blue body to a paler sub-surface. At 0.544 g/cm³ over this block size the body is markedly under-densified — a porous or foamed ceramic variant rather than a fully sintered block, which pulls the 100 MPa number to upper-bound and lets the block lift more easily than its size suggests.