Mineralogy and Geology of apart of Nova Scotia. 325 



ture is distinctly conchoidal. On exposure to the air, the color 

 changes, and the substance becomes black and opaque. 

 This peculiar change is also observed in specimens, before 

 being removed from the rock, even to the depth of six inch- 

 es from the surface. We would observe that this substance 

 from its deceptive appearance has occasioned much specu- 

 lation among the inhabitants, and that a company was form- 

 ed not long since, for the purpose of working it as an ore of 

 copper. This mistake seems to have originated from the 

 use of the mineral rod, which in Nova Scotia, as well as in 

 New England, has led many an honest farmer into ruinous 

 speculations. 



In the possession of a person, residing near this locality, we 

 observed a beautiful cylinder of heulandite. It was twelve 

 inches long, and one in diameter at the largest extremity. 

 Had we not seen before examples of this form, we should have 

 pronounced this specimen to be a stalactite, formed in the lar- 

 ger cavities of the amygdaloid. It consisted of brilliant, 

 transparent laminae, placed at right angles to its axis. Its sur- 

 face was invested with a coating of green earth and seemed 

 as it were, to have been painted artificially. It was found 

 at St. Croix Cove, and obviously filled the entire space of a 

 cavity corresponding with its dimensions. This being a large 

 and very perfect representation of the forms under which 

 this substance there occurs, we were induced to mention it. 



Gates' Mountain is also formed mostly of amygdaloid and 

 the included minerals are peculiarly large and abundant. In 

 obtaining specimens, the labor of digging or even of using 

 a hammer is here entirely avoided ; for masses of thomsonite 

 and mesotype are found abundantly scattered over the fields. 

 Indeed, in some spots, the rock which has resulted from the 

 decomposition of the amygdaloid, is literally filled with mas- 

 ses of these minerals, from the size of a bullet to that of a 

 twenty four pound ball. We shall mention these two min- 

 erals from their remarkably well characterized appearance. 

 The large masses of thomsonite are composed of long and 

 slender crystals, radiating from opposite points of the sur- 

 face, and meeting in the centre, where they unite in a very 

 irregular manner, forming narrow cells in which may be ob- 

 served distinct, colorless and transparent crystals in the pri- 

 mary form, measuring more than an inch in length. These 

 crystals are occasionally replaced on their solid angles and 

 terminal edges, but the replacements are not deep. This 



