Pitchstone

Pitchstone

Pitchstone is a type of glassy lava that has a pitch-like lustre and greenish color, similar to rhyolite. It typically contains a small amount of water in its composition. In thin tabular vitrophyre bodies, pitchstone is characterized by a glassy matrix that contains partly resorbed feldspathic macrocrysts and cumulate fragments.From: A Geology for Engineers [2017], Triassic to Neogene tectono-magmatic events within Lorne Basin evolution, coastal New South Wales, eastern Australia [2020]

Igneous Rocks

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Published in F.G.H. Blyth, M. H. de Freitas, A Geology for Engineers, 2017

F.G.H. Blyth, M. H. de Freitas

Pitchstone, another glassy lava, has a pitch-like lustre and general greenish colour; otherwise resembling rhyolite, pitchstone usually contains a few per cent of water in its composition. Small curved contraction cracks, formed around centres during the cooling of the glass, are known as perlitic structure.

Triassic to Neogene tectono-magmatic events within Lorne Basin evolution, coastal New South Wales, eastern Australia

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Published in Australian Journal of Earth Sciences, 2020

F. L. Sutherland, I. T. Graham, H. Zwingmann, D. J. Och, C. J. Gardner, R. E. Pogson, R. J. Griffiths, A. Lay

One enigmatic magmatic event awaits resolution for its potential connection to Lorne Basin evolution. Minor vitrophyre emplacements are present in the deformed and altered Carboniferous sequence exposed in the eroded floor and walls that cradle the present basin. The thin tabular vitrophyre bodies all show strikingly similar fresh petrology in which a glassy pitchstone matrix contains partly resorbed feldspathic macrocrysts and cumulate fragments (Figure 6a–f; Figure CH47900 a–f, Appendix 3). A Kew vitrophyre analysis gave an alkaline rhyolitic composition (Knutson, 1975).

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Igneous Rocks

Triassic to Neogene tectono-magmatic events within Lorne Basin evolution, coastal New South Wales, eastern Australia