.V>:> Palache and Warren — Chemical Composition and 



The axial ratio calculated from fifty faces of six forms on 

 eight crystals gives the values of the first line below, with 

 which may be compared the ratios of aegirite and acmite as 

 determined by Broo-ger. 













a 



b c 





a 



Aegirite, Quii 



acy 





1-1044 



: 1 : -6043 



73°27' 



Aegirite, Norway, Brogger 



1-09' 



15 



: 1 : -6009 



73 



09 



Acmite 







it 



1-0996 



: 1 : -6012 



73 



11 







Table 



of angles of Aegirii 



'e, Quincy. 









Pa - 



= 5472 



q = '0~i 



62 e = 



•3015 fi - 72°27' 







Calculated 



Measured 





Limits 



No. of 





. 



•' , 





> , 





, ' , 



Faces Quality 





' 









P 



9 



9 











a 100 



90 c 00' 



90°00' 



89°57' 



90 c 00' 





89 c 37'-90°04' 



5 



poor 



6 010 



00 00 



90 00 



00 37 



90 00 







1 



poor 



m 110 



43 35 



90 00 



43 33 



90 00 





43 00 -43 55 



27 



good 



/ 310 



70 42 



90 00 



70 26 



90 00 





69 56 -70 56 



5 



poor 



u 111 



55 50 



47 06 



55 54 



47 08 





55 17 -56 16 

 46 54-47 31 



11 



good 



s 111 



-23 15 



33 20 



-23 40 



33 24 







1 



fail- 



u)331 



48 21 



69 52 



48 29 



69 50 





47 45 -49 13 

 69 36 -70 00 



4 



poor 



* 331 



-37 47 



66 27 



-37 46 



66 42 







1 



poor 



6 551 



46 31 



77 10 



44 46 



77 57 





44 02-45 31 

 77 30 -78 25 



2 



v. poor 



r 112 



-5 32 



16 53 



-5 51 



16 50 





5 16-6 19 



16 40 -16 57 



5 



good 



A 511 



-66 44 



56 50 



-66 40 



56 45 





66 37 -66 44 



2 



v. poor 



dl31 



26 09 



63 39 



26 40 



63 48 





26 19-26 52 

 63 34 -64 03 



3 



good 



The forms w (331), (551), (112), and d(13l) are new to 

 aegirite although all are known on augite. The habit of the 

 Quincy aegirite crystals is shown by figures 6 and 7. 



Optical. — Small crystals or crystal fragments show under 

 the microscope the following pleochrism : 



a = pale to deep green, sometimes with a slight bluish tone. 

 The color naturally varies with the thickness, but also varies 

 quite widely in the same crystal. In fact portions of a crystal 

 may be a very pale green to almost colorless, and the other 

 portions medium to dark green, without there being, however, 

 any other optical variation so far as can be told. 



b = pale yellowish green to almost colorless. 



c = pale yellow to yellowish green ; almost colorless. 



In many crystals the whole or a part may show a brownish- 

 yellow or even reddish-yellow color. This is often most pro- 

 nounced about black oxide (ilmenite) grains and is believed to 

 be a pigment stain of ferruginous character. There appears, 

 at least, to be no regularity in the distribution of the brownish 

 or reddish colorations. The, extinction, a ^ <?', is 6 degrees. 

 Other optical characters appear to be as usual for aegirite. 



