ABSTRACT
Table 6.1 summarizes the chemical formulas suggested for alinite by different investigators. Originally, the formula Can[3(SiO4).(AlO4).O2.Cl] was suggested for this phase, but this oversimplifies the actual situation. In reality, alinite may be stable only if some Mg2+ is also present in the crystalline lattice, substituting for Ca +. The proportions of
SiO4/AlO4 in alinite are not constant, and may vary between about 3.35/0.65 and 3.45/0.55 (Neubauer and Pollmann, 1994). Thus the actual composition of alinite may be most accurately expressed by the formula
Ca10Mg, _,/2 nx/2[(Si04)3+,(A104), _JOJC\\
with 0.35 < x < 0.45. The crystalline lattice of alinite can also accommodate limited amounts
of additional ions, such as Fe3+, P5+, Ti4+, Na+, and K+ (Noudelman et al, 1980; Boikova et al., 1986). At least four modifications of alinite have been identified, and designated a, a', ft, and y (Noudelman and Gadaev, 1986).
