Figure 1: Time-resolved in situ SAXS patterns.

The formation of solids in the experiment with an initial concentration of 50 mmol l⁻¹ CaSO₄ and equilibrated at 12 °C; (I): formation of small primary entities/scatterers as evidenced through the change in I(q)∝q⁻¹ for q>1 nm⁻¹ and I(q)∝q⁰ for q<1 nm⁻¹ (pink and orange dashed lines); (II) development of a structure factor; (III) formation and development of large scattering features evidenced through the increase in intensity at q<1 nm⁻¹; this change followed a dependence of I(q)∝q^−3>a>−4 (where a is the exponent—green dashed line); (IV) growth of the primary species manifesting itself at q>1 nm⁻¹ by the shift of the scattering curves towards lower q values and the gradual decrease in intensity towards I(q)∝q⁻⁴ (blue dashed line); the inset shows a selected scattering curve and indicates the significance of the I(q) dependence of the scattering exponents q (pink, orange and blue dashed lines) pointing out the characteristic features in scattering as described in the main figure.