Fig. 1. Back-scattered SEM images of the first set of experiments, run as a function of the cooling rates (the applied cooling rate is reported on the SEM images); these experiments were run all using Pt wire. On the left column the five trachtic run-products, whereas on the right column the five latitic run-products. The lengths of the white scale bars are equal always to 50 μm.

Fig. 2. a. Texture of sample AW-LAT-0.5. The original BSE-SEM images are reported on the top. The brightness and contrast were varied such to improve the different particular of crystal phase and glass. The major interpenetrated crystal phases correspond to plagioclases, whereas the prismatic to acicular crystal phases with the lighter grey are pyroxenes. The darker grey zones, mainly concentrated among the pyroxene crystals are interpreted as the residual glass melt. The black and white images correspond to the distribution of glass (centre) and pyroxenes (bottom), respectively. b. Texture of sample AW-LAT-0.125. Two original BSE-SEM images are reported on the top and centre. The original brightness and contrast parameters of these two BSE-SEM images were modified such to improve the textural features and particulars. The longer crystal phases correspond to plagioclases, whereas the (two) acicular crystal phases with the lighter grey colours are pyroxenes. Bottom image corresponds to the distribution of plagioclase crystals respect to both glass and pyroxene, respectively. All the scale bars are equal to 100 μm.

Fig. 3. Glass compositions of crystal-free trachyte and latite run-products solidified in the 1) set experiments. The full star and cross symbols refer to trachyte and latite samples, respectively. The same symbols, but empty, refer to the starting compositions. The dashed lines are eye-guide, joining starting and 0.125 °C/min produced glass compositions.

Fig. 4. Textural features of the run-products FW-LAT-0.5. See text for a complete description.

Fig. 5. Textures of the small- and plagioclase-free patch of FW-LAT-0.5 run-product. These two different images are particulars at higher magnifications of the SEM data reported in Fig. 4. See text for a complete description.

Fig. 6. Back-scattered electron images (top) and selected oxide distribution by EPMA map (see text) of the two Latitic run-products FW-LAT-0.5 (left column) and FC-LAT-0.5 (right column) EPMA maps.

Chemical composition of the run-products by EPMA analysis

The number reported in parentheses refers to the standard deviation calculated on at least 15–20 EPMA point analyses, for which the total mass percent were above 99%.

Experiments of set 1) in the thermal range 1300–800 °C

Experiments of set 2) with fixed cooling rate at .5 °C/min