164 



ULENDONITE FROM THE LOWER MARINE SERIES 



The glendonites here are imbedded in a light-coloured, micace- 

 ous mudstone, which is rather calcareous, and contains numerous 

 marine fossils, e.g., 



Mceonia, 3 spp. 

 Pleurophorus sp. 

 Pachydomus sp. 

 Mourlonia rotu7idata(1). 

 Keeneia(]uv .) . 

 Conularia laevigata Morris. 



Plant-st em. 



Spirifer vespertilio G. Sby. 



S. tasmaniensis Morris. 



Martiniopsis subradiata Sby. 



Chwnomya sp. 



Edmondiai}.) nobilissima de Kon. 



Deltopecten subquinquelineatus McCoy; two vars. 



Fig. 2 (p. 163) is a vertical section of part of the Permo-Car- 

 boniferous system, showing the position of the various glendonite- 

 horizons. 



Chemical. — The substance of these pseudomorphs was found to 

 be almost entirely soluble in hydrochloric acid; and qualitative 

 analysis showed that they consist almost wholly of calcium car- 

 bonate, and also that there is an absence of both sulphates, and 

 barium. The composition, then, is no doubt very similar to those 

 analyses by Mr. B. V. Barton, B.E., quoted in the paper mentioned 

 above,* and a quantitative analysis was not considered necessary 

 in this case. 



Crystallographic. —The crystals are all of * 



similar type to those described from Singleton 

 and Glendon, but are somewhat smaller, 

 averaging from 2 to 2*5 inches in length and 

 0*75 inch in diameter. They a re mostly 

 simple crystals, but a number are of the com- 

 posite type. Of those which are not simple, 

 the majority are like that figured(Fig.4), i.e., 

 an intergrowth of two individuals, while a 

 few are much more complex, there being as 

 many as eight individuals bunched together. 



The frequent occurrence of the first of these 



, . , ,, - ' . ,. Fig.4— Photo of simply 



two types, namely, mtergrowths of two inch- °, . , . , • . 



twinned glendonite 



viduals, suggested the possibility of twin- 

 ning. That they are not twinned, however, 



crystal (about nat. 

 size). 



• Kec. Geol. Survey N. S. Wales, viii., pp. 170-172. 



