RoaeErs. | Minerals of the Galena-Joplin District. 479 
less in all the types, are especially prominent in this one. 
Measurements as follows: 
CrysTaL. | Angle measure ererases Calculated. 
WO 1, | BAe [Okt pOVZIT| ~ il 21°30' | 21°37’ 
No, B, | Ge pase 0112,0775 1 28 0 27 51 
No.2. | gaz 02210775 1 8 50 Sea 
No. 2. | gas. 0221,0112 2 38 30 36 52 
No. 8.| 9: az 0221 ,0T75 8 9 43 Oeil 
Nos B | Gps |OPBLAG Teli 4 ON 45 21 37 
No. 3. Ki AK3 9131 A231 3 14 48 1S BS 
No. 3.| #aKe:v| 2181,3121 8 a © BH BE 
No. 3. | ¢- as. 0221 ,0112 2 B70 16 36 52 
Dyexkoy(darnineton) come wht Crm 4 O-n a hi 
No crystals of this type were observed by the writer. The 
following is Farrington’s description” (Dana’s letters being 
replaced by those of Goldschmidt’s for the sake of uniformity.) 
‘“Type specimens in the museum collection come from the 
Meadowcroft mine, Joplin. They are colorless, and not over 
one inch (2.5cm.) inlength. . . . The planes of ¢g. and 
@. are considerably curved, and admit of only approximate 
measurements. The symbol of ¢ was, however, sufficiently 
determined by its relation to the cleavage rhombohedron and 
that of @. was determined from the mean of measurements of 
ten crystals, which gave S. : 6. =0221:0441=49°. he calcu- 
lated value is 49° 32’. The planes of S- are usually smooth 
and bright, those of ¢. are deeply striated parallel to the edge 
g. \@-, and those of @. parallel to the longest diagonal of the 
rhomb. Rounding of the planes of three rhombohedrons S., 
g.", 9. into one another is common. . . . In some crys- 
tals, again, the rhombohedron ¢ is absent, and the crystal is 
made up of only the forms @.,—4R and S.,—4R.”’ A typical 
crystal is shown in figure 39, which is copied from figure 4, 
plate 29, of Farrington’s paper. 
12. Publications of the Field Columbian Museum, Geol. Series, vol. II, No. 7, p. 238, 1900. 
