RoGERs. | Minerals of the Galena-Joplin District. 487 
served on faces of the same form of type 9. Deep etch-pits 
of the form shown in figure 33 are frequent. e: is dull and 
often in oscillatory combination with p-. p- is very much 
etched. The surface of m- has etch-pits of steep, triangular 
shape. 7 and S- appear as smooth faces. Figures 60 and 
71 represent crystals of the type. The following measure- 
ments serve to identify the forms: 
No. of 
CRYSTAL. Angle. measure- Average, Calculated. 
ments. 
nn | | rn 
No. 1. go» AD« 0221,1010 4 AEP TMP || AES BBY 
No. 1. S:. ab 0112,1010 6 63 63 | 68 45 
No. 1. p- Am: 1011,4041 5 31 36 | 31 10% 
No. 1. e:e:¥ 41565146 6 1B id | 1B Se 
No. 1. e: ei 41564516 6 iv. BY | eh YF 
No. 1. K:,K: RIB pABBI II 6 1 46 | TS 
IM@, Jl || GIS / 10% Mae Ilo boo 5000 oo 0 K6 6 11 00 | 10 386 
No. 1. RGA) Pe ee mec rere eer Ree 5 ml BH || WD A 
No. 1. TG AaTa | DCE (A whee ea 6 8 11 0 fl 
No. 2. S. Ag. OIL pAOV@B1k 3 38 BB |) 88 SR 
No. 3. S. a7 01120445 4 12 BO | 12 2 
No. 3. 4 Ags 0445 ,0221 4 94 50 | 24 50 
No. 4. GAN 0221,5051 4 Sf QB | Se wl 
Typr 23. g-, —2R; K:, + R*®; t:, +4R*; S-, —iR; m.-, +4R. 
Small, amber-colored crystals, invariably twinned (O, OR) 
and usually flattened in the direction of one of its lateral axes, 
which makes one of the ¢- faces larger than the others. Figure 
