Mineralogy and Geology of Nova Scotia. 579 



ing veins of quartz, varying from 2 in. in thickness to an 

 eighth of an inch, and less : they have the appearance of having 

 been cleft and again united by the seam of quartz. It appears 

 to be necessary to the formation of. the quartz, that the ex- 

 ternal air should be partially excluded. In the woods, when 

 the mossy turf is removed from a cloven whinstone rock, if 

 the fissure should not be more than 2 in. broad, the op- 

 posite faces of the rock will often be found covered with quartz ; 

 sometimes with very small, glittering, sharp-pointed crystals; 

 often with larger, more opaque, and less perfectly formed 

 crystals; often both faces are covered with solid quartz, and 

 in some places united by it ; while in others a small space re- 

 mains, and points of crystals cover the opposite faces of the 

 quartz. The first crystals that are formed are nearly at right 

 angles with the face of the rock ; but, before the fissure is en- 

 tirely filled up, some are often found in other directions. This 

 circumstance may be caused by the fires which occasionally 

 destroy the turf with which the rocks are covered ; when 

 the fissures being exposed, the crystals become opaque, and 

 sometimes shivered ; and, being on their surfaces in a state of 

 decay, are not continued when a new coat of turf is formed, 

 but new crystals grow from their surface, some of which, 

 being attached to the beveling planes of the points, they form 

 a mass of prisms which are not parallel to each other. 



These veins of quartz occur also in granite and slate. 

 When the veins are 6 in. or more in width in this latter rock, 

 they usually contain embedded broken pieces of slate. There 

 are several other minerals which occasionally fill up veins and 

 cavities in rocks ; but it should be observed, that these mi- 

 nerals are always component parts of the rock in which they 

 are formed. Thus common slate has its fissures united by 

 pyrites ; broad veins of felspar are found it granite ; calca- 

 reous spar forms veins in limestone, sometimes so numerous 

 as to give the idea that it has formerly been cleft into minute 

 pieces like half-slacked lime. There is a pebble approaching 

 to jasper, rarely met with, composed of concentric layers of 

 alternate yellow and brown, which has the same appearance, 

 being very thickly veined with quartz. Near akin to this peb- 

 ble are those rounded depressed lumps of yellowish claystone, 

 sometimes found embedded in sandstone, which always con- 

 tain a blackish nucleus in the centre, at times so much re- 

 sembling a piece of iron rust as almost to give the impression 

 that we may be surveying the remains of an antediluvian im- 

 plement, which, changing to rust, had petrified the surrounding 

 clay, in the same manner that I have seen a somewhat similar 



v v 2 



