Fig. 1. Appearances of iron-rich raw materials
(a): Qingshitou; (b): Hongshitou; (c): Zijintu

Fig. 2. Optical micrographs of iron-rich raw materials
(a), (b): Qingshitou; (c), (d): Hongshitou; (e), (f): Zijintu

Fig. 3. XRD patterns of iron-rich raw materials

Fig. 4. Raman spectra of color-causing mineralsin raw materials
a: Qingshitou; b: Hongshitou; c, d: Zijintu

Fig. 5. Microstructures of glaze surfaces fired from iron-rich raw materials
(a), (b): Qingshitou glaze; (c), (d): Hongshitou glaze; (e), (f): Zijintu glaze

Fig. 6. SEM images and EDS spectra of crystals in the Qingshitou and Zijintu glazes
(a), (b): Qingshitou glaze; (c): Zijintu glaze

Fig. 7. Raman spectra of crystals in the Qingshitou and Zijintu glazes
a: Dendrite; b: Flower-like crystla; c: Rod-like crystla

Fig. 8. Schematic diagram of the crystal formation process in the Qingshitou and Zijintu glazes
(a): Qingshitou glaze; (b): Zijintu glaze