FORMATION OF ENHTDROS OR WATER-STONES. — COOKSET. 9d 



Victoria, and in a later paper in the same volume (page 71) Mr. 

 George Foord more minutely described them, and also gave the 

 results of a qualitative analysis of the liquid contained in one. 

 He found it to be a dilute aqueous solution of chlorides and 

 sulphates of calcium, magnesium and sodium, with a soluble form 

 of silica. The author also sought to explain their formation on 

 the supposition that a certain proportional mixture of colloidal 

 and crystalline silica in solution might have a tendency on deposi- 

 tion to assume a definite crystalline form. 



Prof. A. Liversidge, in the Records of the Australian Museum, 

 p. 1 of the present volume, figured and described two large speci- 

 mens acquired for our Collection, and suggested that they might 

 possibly have been formed by the deposition of silica in hollows 

 or cavities in clay which could have been caused by movements in 

 the clay itself. I have not up to the present been able to find any 

 other literature on the subjVct, with the exception of references 

 to these bodies as pseudo-crystals, enhydros or water-stones. 



A further detailed description is therefore quite unnecessary, 

 but their character may be briefly summed up as follows : — 



They consist usuall\^ of hollow quartz and chalcedonic forma- 

 tions frequently containing liquid, and are bounded externally 

 by smooth perfectly even surfaces meeting in well-formed sharp 

 straight edges. Some of them from their external appearance 

 might easily be mistaken for true crystals, but a closer examina- 

 tion shews that such cannot be the case, for no two surfaces 

 appear to correspond one with the other. This 'fact negatives 

 the supposition that they might possibly be pseudomorphs. In 

 some specimens the walls are formed entirely of chalcedony, in 

 others the outer surface only is chalcedonic, while the interiors 

 are either lined or completely filled up vvith quartz. 



Some exactly similar formations were also discovered in Iredell 

 Co., N. Carolina, America, and seven specimens were sent to this 

 Museum labelled quartz-pseudomorphs after calcite. They are 

 exactly similar in every respect to those from Beechworth, 

 Victoria, with this exception, that five of these specimens are 

 composed entirely of quartz, chalcedony appearing to have played 

 no part whatever in their formation. The sizes of the enhydros 

 in the possession of the Australian Museum range from that of 

 half an inch to that of seven and one-eighth inches in length. 



Leaving out of consideration for the moment their geometric 

 form, most of these enhydros shew such a striking resemblance 

 to many agates, that one is naturally led to the conclusion that 

 a similar mode of formation must be common to all. Prof. 

 Liversidge's suggestion that they ma}' have been formed by 

 the infilling of cavities in clay, seems to me to fail to account 



* Proceedings of the Eoyal Society of Victoria, X., p. 32. 



