142 Mmeralogy and Geology of apart of Nova Scotia. 



angles. The crystals are also so modified, as to assume the 

 form of the dodecahedron composed of two scalene six sided 

 pyramids, applied base to base. Tliey are greatly elongated, 

 and grouped in dehcate stellae, occupying the cavities of the 

 amygdaloid. 



Delicate prismatic crystals, but not of sufficient size to de- 

 termine their form, resembling the Brewsterite from Scot- 

 land, occur scattered through the cavities of the trap tuff and 

 associated with perfect and distinct crystals of analcime, con- 

 stituting interesting specimens. 



The last of the minerals which we shall mention as occur- 

 ring at this locaUty is silicoius sinter. This mineral is usually 

 embraced in the amygdaloid, forming in its spheroidal cavi- 

 ties, a flaky or lamellar crust, which, enveloping their entire in- 

 ner surfaces, sometimes depends in stalactitic projections, on 

 which may be observed small crystals of common limpid 

 quartz. Its color, which is usually snowy white, or greyish 

 white, is in a few instances of a beautiful amethystine tint. 

 One or tvt'O geodes of this substance were found in breccia, 

 which, on being broken, presented internally a bright coating 

 of amethystine sinter with numerous crystals of wine yellow 

 chabasie implanted in, and beautifully contrasted with it. 



The next places to be noticed along the northern shore 

 of the Basin of Mines are the Five Islands, and an eminence 

 known by the title of Tower Hill. Our description of these 

 places will include all that remains to be said relative to the 

 trap rocks of Nova Scotia. These islands form a group 

 situated in a direction south east from the place last descri- 

 bed, and about twelve miles distant. They rise abruptly 

 from the sea, and present for the most part lofty fronts of a 

 picturesque character. Three of the group consist entirely 

 of trap, which from the inaccessible nature of their bases, 

 did not admit of particular examination. If the mineralo- 

 gist however, should select for his excursion a fair day when 

 the turbulancy of the sea has subsided, he will be able to 

 approach their bases, and without leaving the boat, to col- 

 lect many specimens worthy of his visit. The remaining two 

 are composed of sandstone and red shale, exhibiting in 

 some places, the passage of these rocks into a reddish amyg- 

 daloid, vesicular, and zeolitic. In other places, an intermix- 

 ture of the black shale is observed, which sometimes consti- 

 tutes a portion of the amygdaloid, and imparts to it a cor- 

 responding color, more or less evident as it exists in a greater 



