1 882.] Mineralogy. 1033 



but the sub-fibrous mica forms a rii 

 agonal sides and sharp edges. M; 

 completely changed into compact 



Several new localities are given of the alteration of corundum 

 into margarite, fibrolite and cyanite. The interesting fact is re- 

 corded, that since these alterations of corundum occur in rounded 

 masses in the gravel beds of the Southern States, the alterations 

 here described must have taken place prior to the formation of 

 the graveldeposits. 



Of other alterations, those of orthoclase into albite, and of talc 

 into anthophyllite are described. Some very interesting pseudo- 

 morphs of talc after magnetite, from the great serpentine bed in 

 Harford county, Maryland, were observed. Octahedrons of talc, of 

 a white color and pearly lustre, had the scales arranged parallel 

 to the octahedral planes, and sometimes contained a nucleus of 

 magnetite, more or less altered. Dark spots often of definite shape 

 occur throughout the steatite bed, and it is suggested that the 

 entire steatite bed is an alteration from one of magnetite. 



Analyses are given of gahnite from North Carolina and Colo- 

 rado, and some alterations of the latter into a chloritic mineral are 

 described. 



Minute grains of rutile and zircon were detected in the " Edge 



•ctmj) 



act v 



irie 



!x- of p 



yropliyllite. 



having the appe: 



nance of 



kao- 





andr 





Kf.liat 





ited, was describe 











1 lln 





and anthrac 



rite of Drifton, Li 







Pa. ; 



\nalv 



ses 



ofbery 



1 and allaniU 



! from Alexander 



county, N 



i.C, 



ind 



f DIG 



-olit 



:e frotr 



1 Colorado a 



re given, and so 



me octahe 



dral, 







cry 



stals from a furnace 



bottom at Argo, 



Colorado 





;howi 



1 by : 





ysis to 



be probably 



artificial alisonite 







'lie 







■ hi i n 





analyses which 



are espec 



ially 



ralual 



»le fr« 





the we] 



11 known ace 



uracy of Dr. Gen 



th's work. 





Tni 



!■ Paf 



LAG1 



:xe^is < 



>f Minerals, 



—The study of t 



he origin, 



suc- 



ressiv 



e f.,n 



n.iti 



on and 



repeated alt 



srations of minei 



-als, is om 



2 Of 



he m 



ost IV 









■ralogy. As sue! 





pro- 



tress, 



thes 



icier 



ice bee 



omes more g 



eneric, and, enter 



ing a bm, 



tder 



ield, i 



anks 



with gC( 



)gy in unfold 



ing the cosmogoi 



lie truths. 





Of 











one of the most 







hat b 



>• Pn 



.ll-s- 



■or 15. 1 





on the minerals 



f the Deer 



field 



which s 



Chen 



tained. ; 



\:Z: 



it a glan 



lalv^e 



scnpt.o. 



1 give: 



1, is of f; 



1 Amer. 



J u,n, S 



ici., Nov., 



: and of association with other min- 

 :s comparative age. A table is added 



it needed to establish the results ob- 



on of the locality with the exact de- 



f far greater value than any list of chemical 



