Mineralogical notes. No. X. Beryl. Torrington, New South Wales

Abstract

Beryl is a fairly common mineral in the granite area of New England, occurring both in situ. and, more frequently, as rolled crystals and fragments in alluvial deposits. Fine crystals, some of considerable size, have been found in the Torrington district, and in a previous paper crystals from Heffernan's Mine in this locality have been described and figured. The crystals measured up to 6 X 5 cm. and were very simple consisting merely of the prism m (1010) and the base (0001); recently choice crystals of greater complexity have been obtained from this mine and others in the vicinity, and are here described. An interesting feature of some of the crystals is the curious markings they exhibit, particularly on the basal plane. The zonal and parallel growth shown by many of them is also instructive and may afford a clue to the conditions under which they were formed. Occurence and Associates :- According to Mr. J. E Carne, Government Geologist, the beryl at Heffernan's mine, is found in a soft, decomposed, micaceous rook where it occupies vugs containing also quartz, felspar and mica. A specimen in the Australian Museum collection, coming however from another mine in the neighbourhood, consists of a mass of fractured and opaque beryl embedded in black mica. Many of the larger crystals from Heffernan's contain dark inclusions, the nature of which could not be determined, and in one a fragment of smoky quartz is embedded, indicating that quartz probably preceded beryl; some of the beryls are invested, particularly on the base, by a closely adhering skin of silvery mica.