Cement based on hydrated magnesium carbonate (HMC) could be an alternative binder, which significantly reduces CO₂ emission, resulting in potentially negative CO₂ emissions, due to its unique CO₂-consuming hydration process. The hydration product of reactive MgO, in the presence of a carbonate source like hydromagnesite (Mg₅(CO₃)₄(OH)₂·₄H₂O), is a poorly crystalline hydrous carbonate-containing brucite (HCB). The addition of silica or metakaolin induces the formation of magnesium silicate hydrate (M-S-H) or magnesium alumino silicate hydrate (M-A-S-H) and hydrotalcite. Simultaneously, this addition lowers the formation of hydrous carbonate-containing brucite (HCB). In this research, a novel approach by substituting hydromagnesite with nesquehonite (MgCO₃·₃H₂O), a more soluble carbonate source, is introduced, and incorporating a higher proportion of MgO into the mixes with silica or metakaolin. X-ray diffraction (XRD) and Fourier Transform-Infrared spectroscopy (ATR-FTIR) results showed that nesquehonite had completely reacted during 28 days, and promoted the formation of HCB and M-S-H. However, the effect of nesquehonite in the MgO and metakaolin blend system, needs to be further studied. To better understand the reaction kinetics and stability of HCB, more hydration studies at different hydration periods are necessary to be conducted.