438 A. S. Eakle — Allanite Crystals from New Jersey. 



Fig. 5 is a combination having part of the forms shown in 

 fig. 4, with the addition of the clino-dome (o)Y oo(Oll). 



The following is a list of the angles measured and calcu- 

 lated : 



Faces. 



Angles 



meas. 



Angles calc* 



001 : 



: 100 



65 c 



2' 



64' 



3 59' 



001 



: 101 



34 



50 



34 



53 



001 



: 102 



22 



36 



22 



36i 



001 : 



: 201 



89 



2 



W9 



1 



001 : 



: 101 



63 



26 



63 



24 



001 : 



: 102 



34 



15 



34 



15^ 



001 : 



: 103 



21 



22 



22 



io J 



001 : 



; 011 



58 



5 



5S 



92 



z 3 



001 : 



: 111 



52 



8* 



52 



9 



001 ; 



: 111 



74 



50 



74 



49 



100 : 



: 101 



29 



56 



30 



6 



TOO : 



210 



35 



42 



35 



°4 



100 : 



: 111 



49 



35 



49 



40 



100 : 



211 



34 



9 



34 



15 



100 : 



110 



54 



26 



54 



34 



100 : 



201 



25 



59 



26 





210 : 



110 



19 



23 



19 



28^ 



111 : 



III 



61 



41 



61 



38 



102 : 



101 



12 



18 



12 



16i 



201 : 



101 



25 



27+ 



25 



37 



101 : 



102 . 



28 



13" 



28 



8* 



102 : 



103 



12 



27 



11 



56£ 



211 : 



111 



15 



8 



15 



25 



Reflections were so poor in some cases that only approxi- 

 mate readings could be made but a sufficient number of these 

 readings were taken to establish with certainty the identity of 

 all the forms. 



The mineral is so opaque and brittle that very thin sections 

 are difficult to obtain. The sections are brown in transmitted 

 light and show strong pleochroism from deep brown to yellowish 

 brown : a = yellowish brown ; 6 = dark red bcown ; c = dark 

 grayish brown. Absorption c>6>a>. The index of refrac- 

 tion is high while the double refraction appears to be weak. 

 Sections parallel to the orthopinacoid show complete parallel 

 extinction. In the clino-pinacoidal section, the extinction is 

 about 36° from c in the acute angle ft. One section, cut paral- 

 lel to the basal pinacoid, shows a patchwork of reddish-brown 

 and yellowish-green colors resembling an intergrowth. The 

 crystals are abundantly seamed with cleavage cracks and con- 

 tain many inclusions of the associated feldspar. The optical 

 character of the mineral was not determined. 



*E. S. Dana, New System of Mineralogy, 1892, Allanite, p. 522. 



