474 BUTE. MINERALS. 



is abundant on the mainland adjoining, where the same 

 series of rocks occurs ; and has inadvertently been taken 

 for prase. 



Calcareous spar, of a pink colour and nearly trans- 

 parent, is sometimes found in the argillaceous schists ; but 

 generally occupying the cavities completely, or so nearly 

 filling them as to present no decided geometric forms. 



Brown spar is more common ; displaying the ordinary 

 curved rhomboidal figure, and frequently covered with the 

 golden metallic lustre sometimes occurring in this mineral. 

 Another variety is also found, but much more rarely, of 

 a dark red brown colour and very deceptive appearance ; 

 resembling, on a superficial view, the dark red varieties of 

 common felspar. This substance also occurs in some 

 places, in the form of veins, occupying a small space, and 

 often associated with the brown spar and the chlorite. 



In the clay slate, micaceous iron ore is occasionally 

 found ; presenting specimens of great brilliancy, and gene- 

 rally intermixed in veins or rifts with quartz and calcareous 

 spar. The laminae are sometimes thin and prolonged in 

 the shape of ribands, being entangled together or crossing 

 throughout the rock in an irregular manner. Oxidulous 

 iron in the form of octoedral crystals, abounds in the 

 chlorite, or micaceous schist at the northern extremity of 

 the island. These vary from the tenth to the sixth of an 

 inch in length; and, suffering no change from exposure 

 to air, are seen glittering in the sun over the weathered 

 surfaces of the rock ; while they may also be collected in 

 abundance from the gravel formed by its decomposition. 



