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DR. F. H. HATCH AND MR. R. H. RASTAIL ON [ISiOV. I 9 10, 



latter band contains abundant olivine and a transparent, isotropic, 

 very pale green mineral (spinel), with subordinate calcite and a 

 few flakes of mica. 



The olivine possesses the usual characteristics — high refractive 

 index, strong birefringence, and irregular cleavage-cracks. The 

 form is rounded. This mineral, although it no doubt contains a 



Fig. 3. — Photograph of the granite inclusion and the reaction-rim, 

 taken in the Marble Delta Co.'s Quarry, near Port SJiejpstone. 



H. H., photogr 



[The longest diameter of the inclusion = 3 feet. The white patches are 

 flecks of sunlight, the remaining portions of the quarry-face being in shadow.] 



high percentage of magnesia, cannot be classed as forsterite, since 

 chemical tests 1 indicate the presence of a considerable proportion 

 of iron, and the microscope shows a separation of much powdery 



1 Mr. Campbell Smith isolated some of this mineral, and found that it 

 dissolves readily in hydrochloric acid, leaving a residue of white silica. 

 A qualitative analysis showed the presence of silica, ferrous iron, magnesia, 

 and lime, the last-named being possibly due to attached calcite. 



