396 Elements of Mineralogy. 



or run acrofs them in all directions ; thefe* 

 laft are called 'veins. 



The courfe of veins, with relation to the 

 meridian, is called their direction, and with 

 relation to the horizon is called their inclina- 

 tion. 



Their direction, in the language of mi- 

 ners, is denoted by hours; the horizontal 

 circle being divided into twice 12 hours, 12 

 from fouth to north, and 1 2 frorn north to 

 fouth : eaft and weft directions are therefore 

 denoted by 6 o'clock. 



Inconfiderable veins that diverge from the 

 principal are called Jlifs ; confiderable mafles 

 of ore that have no great length are called 

 bellies or Jlock-ivorks ; fo are alfo accumulated 

 veins or thick bodies of ore formed by the 

 junction of feveral veins. 



The ftones which fill the cavities that form 

 the veins are called the matrix (gang) of the 

 ore ; the rocks that lie over the veins are 

 called the roof- thofe that lie under them the 

 Jloor^ and by fome the hading ; the matrix is 

 almoft always a finer fpecies of ftone than 

 the furrounding rocks, though of the fame 

 genus ; even the rocks themfelves are finer 

 grained as they approach the vein. 



There 



