Reviews — Traill on Quartz and Opal. 215 



enclosed by quartz during the process of crystallisation are simply 

 enumerated, no attempt being made to explain the probable mode in 

 which such hair-like crystals as those of rutile, asbestos, etc., are en- 

 closed, those of the former often crossing each other at various angles. 

 In the British Museum is exhibited a very instructive series of crystals 

 and masses of quartz with enclosed minerals, conspicuous among 

 which is a large crystal, said to be from Brazil, enclosing a large 

 cavity containing a fluid, in which are some small loose crystals of 

 iron pjri-ites. The same crystal also encloses several distinct doubly 

 terminated crystals of quartz, and the impressions of some large 

 tabular crystals which were probably mica. Another interesting ex- 

 ample of an Enhydros in the same collection is a small nodule of 

 translucent chalcedony about two and a half inches long by one and 

 a half wide, which is three parts filled with a fluid, no doubt water. 

 This was found near Salto, in Uruguay, by W. G. Lettsom, Esq., and 

 probably represents one stage in the formation of agates. 



Small but perfect rhombohedrons of a red colour have been found 

 in the calcareous geodes, " potatoe-stones," of Somersetshire, and en- 

 closing peroxide of iron, at Wolf's Island, Lake Onega, Government 

 of Olonetz, Eussia. The author places silicious sinter with quartz, 

 whilst all reliable analyses show it to be hydrous ; and its nearly 

 complete solubility in caustic potash, together with its low density, 

 point to the species opal as its'coirect place. He also states that 

 aventurine is often imitated in glass. Is he not aware that the glass 

 is the true aventurine, the name being adopted for a variety of quartz 

 which was somewhat similar in appearance ? A Frenchman dropped 

 some copper filings accidentally, par aventure, into a fused vitreous 

 mixture, and gave the name aventurine to the glittering mass which 

 resulted from this accident. 



As we have shown, this book is of no value to the mineralogist, 

 though the author might have produced a really useful work by 

 giving a little more time and labour to his subject, so as to include 

 the results of the labours of those who have, during the last ten or 

 fifteen years, made these minerals their special study. 



Geological Society of London. — March 20, 1867. — Warington 

 W. Smyth, Esq., M.A., F.E.S., President, in the chair. The follow- 

 ing communications were read : — 



1. " Keport on recent discoveries of gold in New Brunswick." 

 By W. S. Shea, Esq. Communicated by the Eight Hon. the Earl of 

 Carnarvon. 



Mr. Shea gave in his report a detailed account of his explorations 

 into the gold-bearing gravels of certain river valleys in the counties 

 Victoria, Northumberland, Carleton, and York, in Central New 

 Brunswick. He had been enabled therefrom to draw the following 

 inferences : — (1) That the gold in these alluvial deposits is derived 

 from the quartz-veins penetrating the rock of the district ; (2) that 



