164 



shining appearance. The earthy sort at first sight resembles 

 chlorite, but is more or less rhomboidal in its fracture. 

 It seems to be mixed with quartz, and is irregular as to 

 hardness. This green substance is mostly very irregular as 

 to shape. We could only discover a small inclination to 

 hexangular columns with irregular ends : these are some- 

 times smooth and shining, and have whitish transverse 

 stria;, which give them the appearance of an onyx : these 

 striae are softer than the other parts (see the middle figures) : 

 some of these have a resemblance to jade, as Raspe ob- 

 served, but perhaps only from their outward smooth aspect. 

 The lighter ones, we presume, differ only in colour, and are 

 probably the same substance; indeed, Jameson calls them 

 all hornblendes. We have had the pleasure, through the 

 kindness of Mr. Hatchett, of seeing the corundum from 

 Tirie, spoken of by Mr. Jameson, and find it the same sub- 

 stance with these crystals, only much lighter in colour: 

 but, as Mr. Greville observes, they are not fusible, as 

 Kirwan and Jameson say hornblende is, therefore they can- 

 not be hornblende ; nor are they now supposed to be corun- 

 dum, although the external appearance of the lighter varieties 

 much resembles that substance. We, at present, only men- 

 tion these crystals because they occur in the Tirie marble, 

 but must show larger specimens, and explain them further 

 hereafter. 



Mr. Jameson in his Mineralogy of Scotland, v. 2. 30. de- 

 scribes the red-coloured marble of Belephetrich as follows : 



Colour, pale blood red, light flesh red, and reddish white. 



Lustre, none, except from a number of dispersed shining 

 foliae. 



Fracture, fine splinter}'. 



Transparency : transmits light freely at the edges. 



Hardness : yields pretty easily to the knife. 



