]30 ACCOUNT OF A MINERAL SUBSTANCE. 



" with golden ftreaks," which proved to be yellow mica; 

 and it appeared, that it had been fent, with various fpecimens 

 of iron ores, to Sir Hans Sloane, by Mr. Winthrop, of Maf- 

 fechufets. The name of the mine, or place where it was 

 found, is alfo noted in the catalogue ; the writing however is 

 fcarcely legible : it appears to be an Indian name, (Naut- 

 neauge) but I am informed by feveral American gentlemen, 

 that many of the Indian names (by which certain fmall diftricts, 

 hills, &c. were forty or fifty years ago diftinguifhed,) are now 

 totally forgotten, and European names have been adopted in 

 the room of them. This may have been the cafe in the pre- 

 fent inftance ; but, as the other fpecimens fent by Mr. Win- 

 throp were from the mines of Mafiachufets, there is every 

 reafon to believe that the mineral fubftance in queftion came 

 from one of them, although it may not now be eafy to iden- 

 tify the particular mine. 



§ I. DESCRIPTION OF THE ORE. 



Defcription. The external colour is dark brownifh gray. 



The internal colour is the fame, inclining to iron gray. 



The longitudinal fracture is imperfectly lamellated ; and the 

 crofs fracture (hews a fine grain. 



The luftre is vitreous, flightly inclining in fome parts to 

 metallic luftre. 



It is moderately hard, and is very brittle. 



The colour of the ftreak or powder is dark chocolate brown. 



The particles are not attracted by the magnet. 



The fpecific gravity, at temp. 65°, is 5918 *. 



Experiment 1. 



The ore was di- Some of ^ e ore > reduced to fine powder, was digefted in 



gefted in muria- boiling muriatic acid for about one hour. 



tic acid. 



Little aftion. « rp^ e f ij ow ; n g refults of fome experiments which I have pur- 



pofely made, will fhew how much the fpecific gravity of this ore is 

 different from that of Wolfram, and Siberian chromate of iron. 

 Pure Wolfram, free from extraneous fubftances, at tem. 65° 6355, 

 Siberian chromate of iron, containing fome of the green oxide 3728. 

 Pure Siberian chromate of iron - 4355. 



The Siberian chromate of iron, like all other mineral fubftances 

 which are not cryftallized, and which confequently are not always 

 homogeneous, muft evidently be liable to confiderable variations in 

 ipecific gravity. 



The 



