Lieut. Baddeley on Sulphate of Siront.ian, cf-c. 109 



casionally seen. These grains are too small to allow me to dwell 

 much upon their structm-e,* but it may be stated that upon fracture 

 the shining faces of translucent laminae occasionally appear. It 

 scratches glass with ease, but is less hard than felspar. Acid pro- 

 duces no other effect upon it than to disengage a few bubbles of gas, 

 with effervescence, which is owing to the carbonate of lime that enters 

 partially into the composition of the aggregate. Exposed to the 

 greatest heat of the blowpipe, it fuses at the point of the fragment, 

 into a dark brown enamel, and by continuing to urge the fiame, it 

 intumesces by fits and starts, but the portion beyond the blue cone 

 preserves its translucency and color. 



Some of the grains are of a darker color than the others, but the 

 exterior flame of the blowpipe appears to reduce them to the same 

 shade. The darker grains resemble augite, as the lighter colored do 

 olivine. From all varieties of the former it is distinguished by the 

 result of fusion ; from the latter, by its fusibility. 



Most of the white mineral has a fibrously laminar structure. It is 

 translucent; lustre distinctly pearly on the faces of the laminae. It 

 scratches glass slightly. In acid, owing to the carbonate of lime 

 (magnesian ?) with which it is associated, it feebly effervesces. Its 

 powder, thrown on heated charcoal, phosphoresces with a beautiful 

 light green color. f A small fibre fuses readily in the interior flame 

 of the blowpipe into a colorless glass. 



The sp. gr. of the aggregate is 2.96. 



Weather acts unequally upon the surface of this aggregate, leaving 

 it in small furrows and deep striae, occasioned probably by the fact 

 that the white mineral is more readily acted upon and removed. 

 The effect of weather is not confined to the surface, as a reddish 

 band forms a sort of incrustation upon it. 



This aggregate appears to form a bed or thick vein in sienite or 

 granite, (I know not which to call it) and lies in unconformable con- 

 tact with transition limestone. 



(To be continued.) 



* Candor obliges me to add, that the crystallographic characters of minerals are 

 those with which I am least acquainted; by neglecting them, therefore, there will 

 be less risk of misleading. 



1 This phosphorescence is remarkable. In the exterior flame of the blowpipe, a 

 beautiful luminous green light appears to pass through the mineral, rendering it, 

 for the moment, highly translucent. This phenomenon is distinctly visible by can- 

 dle light. This light bears a striking resemblance to that which is often seen to 

 adorn the body of the fire-fly in the West Indies. 



