PETROGKAPHIC GEOLOGY AND DESCRIPTIONS. 797 



Calcite. Pseudamygdaloid.] 



No. 1846. CALCITE. (Cone-in-cone.) 



Prom the slates on the south side of the tongue which divides Pigeon bay into north and south arms. 

 Ref. Annual Report, xxii, page 9. 



Meg. Septaria-like masses, weathering from the slates, having a cone-in-cone 

 vertical structure. 



Mic. The calcite stands with its vertical axis about in agreement with the 

 directions of the cone structure, but it is clouded by dark impurities which are 

 abundant along the cleavages and are much thickened along the undulating or 

 mammillated planes of separation between the individual cones. Two (thick) sections. 



Age. Animikie. 



Remark. When collected this substance was presumed to show possibly some 

 trace of organic structure. It was submitted to Profs. John M. Clark and G-. F. 

 Matthew, and they concur in the opinion that no organic structure is visible. 



N. H. W. 



No. 1847. PSEUDAMYGDALOID. 



At the eastern end of the outer and eastern of the Lucille islands (Magnet island). 

 Ref. Annual Report, xxii, page 9 ; Final Report, vol. iv, page 516. 



Meg. The green spots give this rock an amygdaloidal aspect. It is rather 

 coarse grained. 



Mic. It is due to alteration that this rock has acquired conspicuous delessite 

 areas and a partial uralitization of the augite. This uralite appears as a sharp 

 fringe, with fine fibrous structure, growing out from the augite in precisely the same 

 manner as the fringes of secondary growth, so-called, in the hornblendes of the 

 porphyry at Kekequabic lake, and in several other similar hornblendic rocks. It is 

 particularly well illustrated in the description of some dikes on Stuntz island (Nos. 

 380, 872), where some figures may be seen. It has already been suggested that these 

 fringes are neither "frayed out" ends of the hornblende as suggested by Williams, 

 nor secondary growths as supposed by Van Hise, but that they show the growth of 

 the hornblende beyond the original limits of the augite grains, the difference of 

 absorption and of polarization colors being due in some way to the effect of the 

 augite form in the body of the resultant hornblende. 



In rock No. 1847 this hypothesis is demonstrated, for many of the augites have 



this fringe, while they are not yet wholly converted 

 into hornblende, each mineral having its charac- 

 teristic extinction, angle and colors of double refrac- 

 tion, as illustrated by the diagram below. This shows 

 that a fringe of hornblende is formed about the augite 

 before the ite is changed materially, and that the 



FIG. 48. HOKNBLENDIC FRINGE ON 



fringe is older than the hornblende which later replaces 



