554 Intelligence and Miscellaneous Articles* 



analyses contained a small quantity of substance insoluble in car- 

 bonate of soda, evidently quartz, mechanically intermixed with the 

 finely-fibrous mineral. 



III. is the mineral from Bergen Hill, New Jersey, analysed by 

 Beck. He has erroneously given 6*8 per cent, of magnesia in this 

 mineral. Otherwise, substituting soda for magnesia, his analysis 

 agrees pretty nearly with the one given above, which was done 

 under my direction by Mr. J. S. Kendall. Hayes had also analysed 

 this mineral, and corrected Beck's analysis as far as relates to the 

 absence of magnesia and the presence of soda. He however did not 

 find that it contained water, which is essential to the composition of 

 pectolite. 



IV. is also a fibrous mineral from Bergen Hill, which evidently 

 agrees in composition with pectolite. It differs from the other spe- 

 cimen from the same locality in its fibres being straight, and not 

 grouped together into star-like forms. This analysis was executed 

 at my request by Mr. G. J. Dickinson. 



It is evident that these minerals all agree in chemical composition 

 with the pectolite of Von Kobell, and also in external characters. 

 Slight differences in the results of the analyses may easily be ac- 

 counted for by the difficulty of procuring a finely fibrous mineral in 

 a state of known freedom from intermixture with foreign substances. 



The formula given by Von Kobell for pectolite is — 



3(NaO, 3Si03) + 4(3CaO. 2Si03) + 3H0, 



which formula requires — 



Silica 52-55 



Lime 34-94 



Soda 9-70 



Water 2-79 



99-98 



Frankenheim considers the water in the pectolite as unessential, 

 and allies this mineral with the augite family, from which it differs 

 widely in chemical characters. The constant presence of nearly 

 3 per cent, of water in all the analyses of the substance dried at 

 100° C, makes it highly improbable that it should be merely acci- 

 dental. In fact, the formula given above seems to be the only one 

 which could be adopted for this mineral. 



The original stellite, described by Thomson as occurring in Scot- 

 land, was probably an impure specimen of pectolite, which mineral 

 it agrees with in external characters, as well as in chemical com- 

 position, merely substituting soda for magnesia. The mineral de- 

 scribed by the same chemist under the name of WoUastonite, under 

 the erroneous impression that that name had not been generally 

 adopted for table- spar, is also evidently identical with pectolite.— 

 Boston Journal of Natural History, vol. vi. p. 40. 



