MINERALOGY, 73 



A. In feparate or diftinft rhomboidal 

 criftals, from the iron mine called Moff- 

 grufvan, at Norbery in Weftmanland *. 



SECT. LXVII. 

 Ob s er vat ion on the Siliceous Order: 



The oeconomical ufes of this order are not 

 fo manifold as thofe of the Calcareous and Ar- 

 gillaceous claries -, however, moral reflections laid 

 afide, it will be necefTary briefly to mention how 

 far this order is confidered and employed in com- 

 mon life. 



The Europeans have no farther trouble with 

 the precious Hones, than either to cut them from 

 their natural or rough figure, or to alter them, 

 when they have been badly cut in the Indies ; in 

 which latter circumftance they are called Labora : 

 and it may be obferved, that for cutting the 

 ruby, fpinell, ballas, and chryfolite, the oil of 



* This fpecies is very feldom found alone in form of 

 veins, and ttill more rarely as conftituting the fubftance of 

 whole mountains; but is generally mixed either with quartz 

 and mica, as in the granites, or with jafper, having fome 

 occafional concurring particles of quartz, cockle, and horn- 

 blende, as in the porphyry. II the rhombic quartz and jafper 

 v. ere of the fame fp*cies, ihat fort of porphyry which is 

 made up of thefe two bodies only, ought to be ranked among 

 the jafpers, inflead of being placed with the Saxa in my 

 Appendix, Sect, eclxvi. 



it is however obfervable on old monuments, which are 

 expofed to the open air, that though the porphyry has de- 

 cayed, and consequently loft its polifh, yet grani'.e of the 

 fame age, compoied for the moft part of rhombic quartz, 

 has kept its luftre. This, however, does not contradict 

 the poffibility of rhombic qiartz being of the fame fubftance 

 as the jafper ; becaufe the calcareous fpar is found to bear 

 the weather, and evea fire, better than the limeftone. 



vitriol 



