Note 10 — Chapter II · ETNA.
Reading edition
The view of Professor Judd, that leucite easily changes into felspar, and that some ancient igneous rocks which now contain felspar were originally leucitic, does not seem to be borne out by the above facts. In such cases the felspar crystals ought to retain the forms of leucite. See Volcanoes, 4th edition, p. 268.