225 



was of as great, or perhaps even more immediate, interest than 

 the paper itself. 



The Secretary announced that as the date of their next ordinary 

 meeting was December 27th, and that day had been appointed 

 a Bank Holiday, the Committee had decided that there should be 

 no meeting held on that day. The next Ordinary Meeting of the 

 Club would therefore be held on January 24th, 1911. 



Exhibited by Charles H. Caffyn : Nepheliyie Basanite, from 

 Butterton Hall Park, near Newcastle, Staffs. This rock has 

 recently been described by the Geological Survey as worthy of 

 special comment, and is of interest as being the second rock 

 only known in England to contain nepheline. 



Extract from Summary of Progress for year 1909 of the 

 Geological Survey (published 1910) : 



In the northern part of Staffordshire there is a well-known 

 dyke which is exposed in several quarries at Butterton and 

 Swynnerton. 



Specimens taken from the centre of this dyke in the quarry 

 in Butterton Hall Park prove to be nepheline basanite in 

 excellent preservation. 



The rock consists of olivine, augite, plagioclase, felspar and 

 nepheline. At first glance a microscopic section of this dyke 

 is much like a fresh and rather fine-grained olivine dolerite. 

 The abundant olivine is micro-porphyritic and not easily detected 

 in the hand specimen without the aid of a lens. Purplish-brown 

 zonal augite appears in small eumorphic crystals, but is seldom 

 porphyritic. Minute lathes of polysynthetic felspar are numerous 

 in the ground mass ; from their extinction angles and refractive 

 indices they seem to belong to labradorite. In addition to 

 these, a clear transparent mineral with low double refraction 

 and a distinct cleavage fills up the interstitial areas left after 

 crystallisation of pyroxene and felspar. This mineral has the 

 cleavage and refractive index of nepheline, and stains readily ; 

 it is entirely undecomposed, and in this respect no other nephe- 

 line-bearing rock in Britain can compare with it. 



For a long time the Wolf Pock phonolite has been the only 

 English rock which is known to contain nepheline, and the 

 addition of a basic type is of some interest. The Wolf Pock 

 is generally considered of Tertiary age; the Butterton dyke 

 has a north-north-west trend and cuts and bakes the Keuper 



