484 University Geological Survey of Kansas. 
Adamo Ey eRe Soles 8 Too) arity 8 Shy ——teltn? Cop aeediss JD, silane 
Ghyarslts Os Qesys WR. 
Small, colorless crystals from the Mascot mine, Granby. 
The presence of the low rhombohedrons is of interest, for 
such forms are of rare occurrence. ‘Their intersection edges 
are not sharp. ‘The determination of d- rests upon the fact 
that it truncates the polar edges of S-, as no measurements 
were possible on account of its small size and dull surface. 
e- is a subordinate form and is only found on crystals of this 
type. D- appears as very small faces. The crystals of this 
type are illustrated in figure 51. Following are some of the 
measurements made: 
No. of 
CRYSTAL. Angle. measure- Average. Calculated. 
ments. 
es c,d 
Nai | Gam | A02%plonl | § 24° 5! 23° 5) 
Typr 15. w:,+2R’?; K-,—-R; P-, +R; ¢-, —2R; m-, 4h; 
b, oR; 8-, —4R; K:, +R’. 
Large, light amber crystals with amethystine tints, from 
the Elizabeth mine, Joplin, are designated as type 15. The 
dominant form, w:, has its faces roughened with striations 
parallel to its acute polar edges. The negative unit rhombo- 
hedron is very dull. p- has the characteristic etch-pits as 
shown in figure 27. On the faces of m- are etch-pits as ex- 
hibited in figure 52. An average crystal is represented in 
figure 53. The forms were identified by the following meas- 
urements : 
No. of 
CRYSTAL. Angle. measure- Average. Calculated. 
ments. 
1 3 47° 40’ 49° 23’ 
1 3 16 50 16 00 
1. 2, 89 15 | 89 13 
No. 1. | m. aK. | 4041,1011 1 59 30 59 364 
2) p- am. | L011 ,A404 1 1 32 00 31 105 
| Te ALD 1011,1010 3 45 43 45 93% 
2. | g Ab 0221,1010 4 BY NO Damas 
