The transition of magnesite to magnesia has been achieved by heat treatment at temperatures above 600 \({}^{\circ}\)C. This transition from carbonate to oxide by release of carbon dioxide (CO\({}_{2}\)) initially produces a porous microstructure with low bulk density. Moreover, this material is characterized as a strong reactive due to its low magnesia particle sizes with high surface areas which can be retained if not heated further. Such high surface area variants of magnesia are known as \"active magnesia\" in cement-related research. Exposing this porous form to higher temperatures (>1200 \({}^{\circ}\)C) solidifies the structure by a sintering mechanism and drastically reduces the reactive surface area as well as the affected sites that promote wetting and dissociation of magnesia in acid phosphate solutions. Magnesia-based cements, by definition, use MgO as a building block rather than the CaO which represents more than 60% of the elemental composition of PC. Due to the substantially different chemistry of MgO compared to that of CaO, one cannot simply change the feedstock for conventional Ca-based cements to produce a directly corresponding material using the same infrastructure. Comparing the respective (MgO, CaO)-Al\({}_{2}\)O\({}_{3}\)-SiO\({}_{2}\) ternary phase diagrams, vast differences in chemistry and phase formation are shown. More specifically, no magnesium silicate phases are formed in high temperatures that have hydraulic properties akin to those formed in the calcium-rich region of the CaO-SiO\({}_{2}\)-Al\({}_{2}\)O\({}_{3}\) system: Ca\({}_{3}\)SiO\({}_{5}\), Ca\({}_{2}\)SiO\({}_{4}\), and Ca\({}_{3}\)Al\({}_{2}\)O\({}_{6}\) are critical hydraulic phases in PC, but have no magnesian analogues. Currently, the MEA used in the market is mainly produced by the calcining of magnetite. However, with the continuous mining of mineral resources, the problems of resource exhaustion and environmental pollution are becoming more and more threatening. Following governments' instructions regarding the mining of nonrenewable mineral resources, magnesite resources are decreasing [14] while, at the same time, a large amount of magnesite is discarded annually. These gradually accumulated large amounts of magnesite not only occupy cultivated land but also cause waste of resources. Magnesite is a raw material used in different industrial applications. It is used mainly after heat treatment for the production of caustic magnesia and dead burned magnesia, whilst untreated magnesite has a few industrial applications too (e.g., in the production of fertilizers, electrodes, and environmental protection). The main magnesite deposits in Greece appear in Chalkidiki and Evoia Island. Regarding the case of Evoia's magnesite deposits, they have been started to be exploited since 1893 mainly for the production of magnesia-rich raw materials and refractory final products. In this area, the proven, probable, and possible reserves have been approximately estimated as 35, 45, and 60 million tons, respectively [15]. The concession areas cover \(\sim\)404 km\({}^{2}\) while all mines are within a 14 km radius around the refractory industry plants. The last is 2 km away from the loading port. According to the current activities, the annual capacity is 120,000 MT of caustic magnesia and dead burned magnesia, while above 250,000 tons of stockpile waste have been disposed of in the area during last year's activities. They consist of the fine ore (\(-\)40 mm) which is rejected before the beneficiation processing and specifically before the hand-sorting stage of magnesite. This tailing contains significant amounts of magnesite, and in this work, the feasibility of its utilization as MEA is studied. In the Greek market, materials of similar quality are found, but they are produced from natural mineral raw materials and not from byproducts. The real contribution of such initiatives does not result in a notable decrease in negative externalities. This fact can be assigned to a limited acceptance of \"greener\" building materials [16].