High-temperature phase transition and local structure of a hydrous anorthoclase

Comment on “Water decreases displacive phase transition temperature in alkali feldspar” by Liu et al. (2018)

“…On the other hand, the unit cell volume is a good indicator of the Or content of alkali feldspars. Applying the respective equation of Kroll et al (1986) results in Or19.8, which is dramatically different from Or41 of Yang et al (2016).…”

“…Data availability. Data were taken from the literature (Kroll et al, 1980;Harlow, 1982;Salje 1986;Yang et al, 2016;Liu et al, 2018).…”

“…Although a large number of T c values is available for comparison, Liu et al (2018) chose only five data (their Fig. 9a): one from an earlier paper of the authors (Yang et al, 2016), one from Salje (1986), and three others from Harlow (1982). Unfortunately, the data of Harlow were adopted from Yang et al (2016) where they have already been confused.…”

“…9a): one from an earlier paper of the authors (Yang et al, 2016), one from Salje (1986), and three others from Harlow (1982). Unfortunately, the data of Harlow were adopted from Yang et al (2016) where they have already been confused. Harlow (1982) investigated three anorthoclases and reported three transition temperatures: 183, 395, and 683 • C (his Fig.…”

“…In any case, the great discrepancies between the two Or contents of the critical sample no. 1 of Liu et al (2018) and of the sample of Yang et al (2016) need to be clarified.…”