Mn₄Na₈O₂₀Si₆

Architectural potential

A manganese-modified soda-silicate glass fired at 1150 °C, carrying 500 MPa of compressive strength and the full supply-chain and safety scores of ordinary float-glass practice. Embodied CO₂ is within two per cent of float, but the energy overhead runs sixty-two per cent lower thanks to the manganese flux depressing the working temperature. That combination places this glass directly in the structural-translucent register against float: pressed stair treads in a gallery mezzanine, floor panels walked on from above in a reading-room mezzanine, transparent partitions in an operating-theatre ante-room where a tinted purple-brown filter is wanted without adding a separate interlayer, light wells above a cloistered courtyard, and column-like light-admitting piers for a pavilion where the tinted body reads as built colour rather than applied film. The HIGH-confidence rating on the compression figure and the full supply-chain score make this one of the more specifiable translucent structural candidates in the atlas. The caveat is colour commitment: the purple-brown body is intrinsic to the manganese loading, not an interlayer, so a specification sees the tint everywhere — edges, crown, entire footprint — and cannot be reversed in fabrication.

Material character

A purple-brown transmitted face with amber undertones where the slab thickens along the 47 mm edge — manganese-stained glass in the historical sense, shifted warmer by the soda-silicate host. Fully translucent rather than transparent: silhouettes read through, detail does not. At 2.96 g/cm³ and 85×85×47 mm the slab is firm two-handed, lighter than the borosilicate family at the same footprint. Surface carries the pressed-glass striation — three faint anneal lines close to one long edge — and the crown sits under a low convex rise. Edges cold-cut, lapidary-bloomed. Against ordinary float the body is thicker, warmer, and holds its own under side-lighting.