Notes on a specimen of Basalt-glass (Tachylyte) from near Macquarie plains Tasmania, with remarks on Obsidian " Buttons."

The absence of any reference in the records of this Society to the class of volcanic products to which basalt-glass belongs may justify a brief account of the history and character of the specimen now exhibited. It was originally about two and a half inches long and two inches thick, irregularly angular in shape. The colour is a dark olive-green, but a weathered face is bright blue ; the fracture is conchoidal.
This specimen was obtained by me many years ago from a heap of basalt and scoriae, excavated from a temporary road-cutting on the right bank of the Derwent between Macquarie Plains and Fenton Forest. Near the same spot I found, on a block of basalt, thin bands of a dull black glass, bearing some resemblance to the glassy selvages of basalt dykes, which have often been described as constituting the chief sources of obsidian and basalt-glass. The basalt of this part of the district is probably of late tertiary age. Includes woodcut of Volcanic Bomb