Etna : a history of the mountain and of its eruptions . 3 9. AD. I bS9 FRANK RUTLEY DEL. & C° Sc SECTIONS OF ETNA LAVAS SEEN UNDER THE MICROSCOPE. - THE LAVAS. 130 lamellae. Zirkel has noted the plentiful occurrence ofthese glass inclosures in the felspar crystals andfragments of crystals which partly constitute thevolcanic sands of Etna, in which he has also detectedthe presence of numerous isolated particles of The felspar microliths, which constitute so largea proportion of the ground-mass in the Etna lavas, arein most instances probably triclinic. Monoclinic f

---

Etna : a history of the mountain and of its eruptions . 3 9. AD. I bS9 FRANK RUTLEY DEL. & C° Sc SECTIONS OF ETNA LAVAS SEEN UNDER THE MICROSCOPE. - THE LAVAS. 130 lamellae. Zirkel has noted the plentiful occurrence ofthese glass inclosures in the felspar crystals andfragments of crystals which partly constitute thevolcanic sands of Etna, in which he has also detectedthe presence of numerous isolated particles of The felspar microliths, which constitute so largea proportion of the ground-mass in the Etna lavas, arein most instances probably triclinic. Monoclinic felspardoes, however, occur in some of these rocks ; but thedifficulty of ascertaining the precise character of mi-croliths renders it unsafe to speculate on the amountof sanidine which may be present. Some crystals,such as that shown in the centre of Fig. 2, appear atfirst sight to be sanidine, twinned on the Carlsbadtype, but closer inspection often demonstrates thepresence of other and very delicate twin lamellae. The augite in these lavas sometimes occu

---

Size: 1569px × 1593px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No

Keywords: ., bookauthor, bookcentury1800, bookdecade1870, booksubjectvolcanoes