136 EDSON S. BASTIN 



^^^'' F^.=86y8=<^ =^' perfemane. 



POM 6^ 2C 



Subclass — ;— = — — -'^ = < r > i =2, dofemone. 



A 23.53 



Order -r-;r =^ — '- — = < r>i- =2, dopolic, Mainare. 



M 10.00 ^ 



P 22.06 



Section — = = < l>f = S> pyrolic, Mainiare. 



O 30.99 



(MgFe)0 + CaO 29.63 



^^"g K.O + Na.O ==T^=>^^^' P^™^^^^- 



^ . (MgFe)O 27.85 ^ , 



Section ^ r^ = o = >f =1. perminc. 



CaO 1 . 78 ^ 



MeO 21.97 



Subrang „ 7^ = — w^= <t>I =2, domagnesic, Lermondose 



reU 5'"° 



Since the rock shows a slight amount of akeration the norm 

 computed above can be regarded only as approximating that of the 

 fresh rock. The rock, however, falls well within the limits of each 

 of the divisions in the above classification, and it is not probable 

 that the weathering has produced changes sufficient to change its 

 position in the quantitative classification. 



The name Lermondose which is here proposed for the rock is 

 derived from Lermond Pond, situated about one mile northeast of its 

 type exposure. The ordinal name Mainare is a reference to the 

 state of Maine, in which the rock occurs. 



Bearing on the origin of certain sulphide ores. — Chalcopyrite is 

 present in such small amounts and the percentages of nickel and 

 cobalt associated with the pyrrhotite are so small that the rock has 

 no present economic value as an ore. The sulphides are also asso- 

 ciated in such an intimate way with the other rock minerals as to 

 make their complete separation difficult. The rock, nevertheless, 

 exhibits an unusual concentration of metallic sulphides common in 

 many ore deposits, and from a theoretical standpoint at least may be 

 regarded as an example of ore formed by original crystallization from 

 the molten magma. It seems but a short step from a rock of this 

 type to one in which chalcopyrite is present in sufficient amounts 

 or in which the percentage of nickel or cobalt in the pyrrhotite is 

 large enough to give the ore commercial value. The existence of 

 commercial deposits of sulphide ores of such purely igneous origin 

 has, so far as known to the writer, never been satisfactorily demon- 



