ELLS HA MITCHELL SCIENTIFIC SOCIETY. 



61 



occur frequently in magnificent crystallizations. Crystals of 

 considerable magnitude have been found in Clay county, Yancey 

 county (near Hurricane Mt.), in Michell county (near Bakers- 

 ville) and in many localities in Burke, Iredell and Alexander 

 counties. Notable quantities have come from Clay and Chero- 

 kee counties, and from Lincoln county, near Lincolnton. To 

 Alexander county, however, the credit must be given of having 

 produced the most beautiful rutile crystals known to science. 

 Rutile is found there in a similar situation to the gems and 

 quartz crystals, /. e., in open pockets; in fact, it is found inti- 

 mately associated with and implanted upon the gems and often 

 preponderates over all the other crystal contents. The particu- 

 lar points of difference over the same product from other regions 

 are their mode of occurrence, beautiful natural polish and crys- 

 tallographic features. Their color ranges from jet black to clear 

 ruby-red and pale-yellow. They range from those of minute 

 sizes to rare examples three inches long and half inch diameter. 

 Their lustre in some cases ap|)roaches that of polished steel. 

 Gems have been cut from the most solid crystals and the result 

 compares favorably with the rare black diamonds from Brazil. 

 Only experts could tell them apart. 



The axial ratio was determined 

 anew on these crystals, and meas- 

 urements of the angles gave results 

 remarkable for their close agree- 

 ment to the calculated angles.* Five 

 new planes were also added to the 

 species, four of which were discov- 

 ered on two crystals found by the 

 author in Sharpens Township, Alex- 

 ander county, at the Emerald mine. 



Curiously jointed, mitred and reticulated crystals and also 

 masses of crystals thus united have been commonly met with; 

 all of which are found to follow certain arbitrary twinning laws 



Highly-modified Rutile. 

 (Basal View). 



*C over s (0001, O over 111, 1) = 137° 39' 52". a : c = 1 : 0.644252, Washington. 



