146 Prof. Maskelyne and Dr. Lang's Miner alogical Notes, 



The planes hitherto known on Gadolinite are* 



10 0, 001, 110, 101, 102, 111, 112. 



In addition to these I have found the new planes 



210, 014, 211, 322, 423,— 



fig. 9, Plate III. representing the poles of all these planes. 



From the angles measured by Nordenskjold with only the 

 hand-goniometer, we deduce the elements f 



a: b :c=l: 0-16249: 1*8780. 



They represent also my measurements (which on the crystals of 

 Gadolinite can never be made with great accuracy) sufficiently 

 well, and with them are calculated the angles of the following 

 Table:- 





100. 



10. 



001. 



110. 



110 

 210 



o / 



58 

 38 40 



/ 



32 

 51 20 



90° 

 90 



/ 





 19 20 



201 

 101 

 102 



19 5/ 

 35 58 

 55 26 



90 

 90 

 90 



70 3 

 54 2 

 34 34 



60 7 

 64 36 

 72 30 



014 



90 



61 8 



28 52 



65 50 



111 

 112 

 211 

 322 

 423 



60 21 

 65 10 

 41 18 

 49 31 

 44 3 



37 41 

 47 46 

 46 10 



53 3 



54 54 



68 58 

 52 26 

 74 11 

 71 42 

 66 59 



21 2 

 37 34 

 24 47 

 21 20 

 29 43 



The following observed combinations are represented in 

 Plate III. 



Pig. 1.— 001, 110, 101, 10 2, 111, 112. 



Fig. 3.— 100, 001, 110, 210, 101, 210, 211. 



Fig. 4.— 100, 010, 110, 210, 101, 102, 111. 



* In the ' Handbook of Mineralogy ' by Brooke and Miller, a plane, e, 

 parallel to the axis b is given with an angle ee' = 33° 34', so that the symbol 

 of that plane would become nearly (014). But as the crystal measured 

 by Miller is the same as that investigated by Phillips, a comparison of the 

 two measurements shows that the above angle is very probably to be taken 

 as the inclination e, 1 0. As the calculated angle 1 2 . 1 = 34° 34' 

 comes near to the former angle, the symbol of the plane e is certainly (10 2). 



t The elements which I had deduced from my measurements before I 

 became acquainted with Nordenskj old's memoirs are 



a: 6 :c = 1:0-6289: 1-3746. 



