Prof. Maskelyne and Dr. Lang's Miner alogical Notes. 147 



These forms were observed on large crystals from Ytterby, 

 Sweden. The crystals are of an opake green material, which is 

 traversed by white veins : they may perhaps be only pseudomor- 

 phous, after the forms of real Gadolimte. The planes are here 

 and there brilliant. 



I found on the crystals figs. 1 and 4, 



110.010 = 32 15 32 6 calc. 



210.110 = 21 appr. 19 20 „ 

 102.001 = 34 28 34 34 „ 



102.101 = 19 10 19 28 „ 



110.102 = 72 31 72 30 „ 



110.111 = 21 25 21 2 „ 

 1-11.112 = 17 appr. 16 32 „ 



The crystal fig. 3, the right half of which only was developed, 

 could only be measured with the hand-goniometer, and gave 



101.101=74 7°1 56 calc. 

 110.211=25 24 47,, 



2 1 I being in the zone [110, 1 I] . 



Fig. 2.— 100, 001, 110, 201, 101, 102. 



A large black crystal engaged in reddish felspar from Ytterby. 

 I found with the hand-goniometer, 



001.102 = 34 34 34 calc. 

 102.101 = 191 19 58 „ 

 101.201 = 16 16 1 „ 



Fig. 5.— 001, 110, 210, 102, 111, 112, 014, 322. 



A detached black crystal, of which fig. 6 gives a vertical pro- 

 jection. The symbols of the new planes 014 and 3 2 2, the 

 latter in the zone [110, 10 2], are deduced from the following 

 approximate measurements : — 



1 4 1 = 29 28 52 calc. 

 110 322 = 22 21 20 „ 

 1 1 2 1 = 201 19 20 „ 



Fig. 7.— 001, 110, 210, 101, 102, 111, 423. 



The half of a smaller black crystal, which in fig. 8 is repre- 

 sented in vertical projection. The faces reflect the light very 

 badly. The following angles are therefore only very rough ap- 

 proximations : — 



110.210 = 17-18 21 20 calc. 

 111.423= 16 18 1 „ 



4 2 3 being in the zone [111, 1 1 0] . 



L2 



