<p>This study proposes the use of an Fe-rich vitreous glass as a novel supplementary cementitious material (SCM) for blended cements. Such materials can be derived from Fe-rich streams, including largely underutilized metallurgical residues or low-grade Fe-containing ores. In this case study, bauxite residue, the waste of the alumina digestion process, was used to produce a material primarily composed of an Al₂O₃–SiO₂–CaO–FeO–Na₂O amorphous phase (vitrified bauxite residue, VBR). The reactivity of VBR was comparable to calcareous fly ash and ground granulated blast furnace slag, while the reactivity of the amorphous phase by itself was more comparable to calcined metakaolin. Triisopropanolamine, employed as both a grinding aid and chemical activator, significantly enhanced the material's reactivity. Incorporating limestone mitigated the inhibitory effects of Fe(II) on early cement hydration, promoted monocarboaluminate formation, stabilized ettringite, and improved strength development, resulting in a dense, low-permeability microstructure. Notably, VBR exhibited excellent workability without requiring PCE-based superplasticizers, though their use further enhanced performance. To address concerns related to using alkaline residues as primary raw materials, the study evaluated heavy metal release, drying shrinkage, and alkali-silica reaction. Remarkably, VBR showed improved aspects to Portland cement, with similar or lower metalloid release, reduced drying shrinkage, and expansion due to alkali-silica reaction in a simulated pore solution pH. Since iron is present in many unexploited, natural, and anthropogenic resources in an uncarbonated form, it holds significant potential as a raw material for producing supplementary cementitious materials.</p> Graphical Abstract <p></p>