146 Journal of the Mitchell Society [March 



Mn 2.33%, but this analysis is of a selected sample from which ma- 

 terial other than magnetite has been removed as thoroughly as possible 

 b}' careful hand-picking. The ore furnished to the Cranberrj' Furnace 

 is shipped as taken from the mine, without crushing and careful se- 

 lection. This, therefore, is much lower in iron, and indeed consider- 

 ably lower than the minimum limit for ordinary magnetic ore ; but 

 because of its extremely low phosphorus and high calcium is acceptable. 



Some of the marble-magnetite is too poor in iron to be regarded 

 as an ore, but by rejecting this the balance passes as an ore which 

 though possibly low grade with respect to iron is available to the 

 furnace because practically all the material that is not iron is a mix- 

 ture of calcite and dolomite which serves as a flux. An anah'sis of an 

 average specimen of the marble made in the laboratory of the U. S. 

 Geol. Survey by Mr. Fairchild gave: MgO = 9.17 ^r, CaO = 26.32%, 

 and CO., = 34.28%, corresponding to a mixture of MgCO.^ and CaCOg 

 in the proportions 1 :2, and an excess of 31/9% COo, a large part of 

 which is in MnCOo. 



Analyses of many carload lots of ore made at the Cranberry Fur- 

 nace at Johnson City prior to the summer of 1919 showed limits of 

 36.43-52.93 for Fe and .0094-.0n4 for P. A series of analyses of 7 

 cars received during the summer of 1919 gave :^ 



Iron 40.65 42.76 46.46 39.07 40.65 35.11 38.54 



Fhosphorus 006ii .0052 .0052 .0052 .0042 .0062 .0057 



One analysis'' of a car of ore very low in iron yielded Fe = 30.52, 

 P = .0052 and CaO = 17.84. This is equivalent to 42.14% magnetite 

 and 31.867o CaCO., or a total of 76%. There was no record made of 

 the other 24%. 



The Ore Body : — The ore body of the mine is reached by a tunnel 

 running 150 feet into the base of tlie hill just above the level of Horse 

 Creek in a direction N. 40° E. It is in the foot wall, Avhich is a light 

 gray hornblendic gneiss that may belong with Keith's Cranl)erry 

 granite, which is archean in age. Between this gneiss and the ore- 

 body is a thin layer of gray mica schist, that may readily be a result 

 of shearing of the gneiss along the contact. Immediately above the 

 ore is another thin sheet of a similar schist and above this a light gray 

 fine-grained gneiss that may be a part of the Cranberry granite. 



5 Furnished by Pres. F. P. Howe, Cranberry Furnace Co., Johnson City, Tenn. 

 " Made by Cranberry Furnace Co. Furnished by Mr. Cooke. 



