60 



JOURNAL OF THE 



found. Instead of being long prismatic tliey presented mostly 

 terminal planes in great number^ as the two figures here show. 



rre 



/^^^ 



in. 



HIGHLY MODIFIED APATITE CRYSTAL, FROM ALEXANDER COUNTY; 



FIGURED BY H. S. WASHINGTON. 



Fourteen different forms were identified, twelve of which 

 appear in the above figure. A normal development would pre- 

 sent one hundred and thirty-four 

 planes on each crystal, while only 

 twenty planes are found ordinarily 

 on apatite. 



Tiie angle of tiie base c (0001) on 

 the unit pyramid x (101 1) was found 

 to be 139° 44J' and the axial ratio 

 as 1 : 0.734335.* 



A twin crystal of apatite, the first 

 to be describedf and credited to the 

 species, is here figured. It was found with the slender crystals 

 above noted. The twinning plane was discovered to be s (1121, 

 2-2). 



Excepting the green and purple ai)atite from Mt. Auburn, 

 Maine, none has been found in the United States more highly 

 interesting: or more beautiful. 



RUTILE (pure titanic acid, Ti O.^). — This mineral is not used 

 to any great extent commercially, and no very large deposits 

 have been found in this State, but it has been proved to have a 

 very ireneral distribution throuirhout the Piedmont belt and to 



^^^ 



Twin of Apatite, 

 Alexander Co. 



*Am. Jour. Sci., June, 1887, p. 504, Hidden and Wasliington. fllji^- 



