Prof. How on the Mineralogy of Nova Scotia. 135 



centages from the well-established formula, that in this case 

 there is no variation from the normal composition, except what 

 is frequent in the species, a replacement of lime by soda. 



Sphwrostilbite. — Among the forms of stilbite occurring here 

 are to be observed crystalline incrustations on various mine- 

 rals ; calcite and apophyllite, for example, and crystals of stil- 

 bite are sometimes coated with layers of a mineral which seems 

 altogether destitute of crystalline structure. I have collected, 

 near Hall's Harbour, a number of specimens showing most 

 curious concretionary structure. In several of these the ex- 

 ternal surfaces are perfectly smooth and rounded; and I should 

 have considered them to be sphserostilbite ; only, while agreeing 

 in blowpipe characters, and seeming to pass in a suite of spe- 

 cimens directly from well-defined stilbite into such forms, they 

 refused to gelatinize. But since I found that, according to 

 Heddle, the gelatinization of sphserostilbite is in reality due to 

 mesolite, and as I can find no appearance of this mineral in 

 these specimens, I think they may be fairly placed in this 

 subdivision (Dana's ( Mineralogy,' fifth edition, p. 443). I 

 have found a more distinctly marked appearance of spheres, 

 about the size of small shot, in a travelled specimen at Hants 

 Port, at the mouth of the river Avon near Windsor ; the little 

 spheres are colourless and behave like those just mentioned ; 

 they show no mesolite ; they fill a drusy cavity in crystalline 

 trap, no doubt drifted from the south shore of the Bay of 

 Fundy. 



Cylindroid of various Minerals filling a Vapour-tube. — 

 Upon one occasion I found in the trap near Morden, King's Co., 

 a rather curious specimen, looking like a green rod running 

 through the rock. There was a considerable length of it ex- 

 posed; and I detached a few pieces, of which the longest mea- 

 sured several inches. They were quite solid, not round, but 

 cylindroidal in form, about 2 inches in diameter. The green 

 coating was probably Poonah earth ; the interior contained a 

 little of the same in patches and minute points throughout ; 

 but the great bulk of the mass was a mixture of dissimilar mi- 

 nerals, one of which agreed in appearance and leading charac- 

 ters with that variety of stilbite of which an analysis is given 

 above, while the most abundant of the others was a fibrous 

 mineral, dull and colourless ; underlying these was apparently 

 mordenite ; there was also a red mineral in small points with 

 diverging lines. Analysis of what seemed to be stilbite (I.) 

 and of the other part (II.) gave these results — 



