Dear colleagues,
We all know that "biotite" is common in potassic alteration related to porphyry-Cu systems. Biotite, however, is not a species name but a series between annite and phlogopite (and fluorophlogopite and fluorotetraferriphlogopite).
Is there any description of fluorophlogopite in potassic alteration zones associated to calc-alkaline porphyries? Is the occurrence of fluorophlogopite restricted to benmoreitic (alkaline s.l.) lavas as described in Mt. Etna, Italy (cf. Gianfagna et al., 2007, Am. Mineral. 92, 1601-1609; Scodari et al., 2013, Am. Mineral. 98, 1017-1025)?