IO0o NEW YORK STATE MUSEUM 
In the rhombohedral ‘zone the negative rhombohedrons 3. (0112), 
g. (0221) and &.(0.11.11.1) are present, the latter only on crystals of the 
rhombohedral habit. Two positive scalenohedrons of the zone [1011.1120], 
M: (7.4.11.3) and P:(3251) are present on crystals of the rhombohedral 
habit, the former of which is also present in larger development on the 
prismatic-rhombohedral crystals [fig. 5]. The planes of these forms are 
striated parallel to the zone yielding only fair reflections. The positive 
scalenohedron 8: (8.4.12.1) and the negative scalenohedron }: (1341) are 
present as modifying planes of comparatively small development on crystals 
of the prismatic-rhombohedral type. The faces are of moderate brilliancy 
and yield fair reflections. Crystals of this type evidently represent an 
advanced stage of crystal deposition and may be regarded as the latter end 
of the genetic series. 
The zonal relations of occurring forms is shown in the stereographic 
projection, plate 16. The distribution of forms with respect to the four 
types is given in the following table: 
SUMMARY OF DISTRIBUTION OF FORMS 
NAUMANN BRAVAIS-MILLER TYPE | TYPE | TYPE | TYPE 
LETTER 
SYMBOL SYMBOL I II II IV 
2). coo P2 1120 soles xe aes x 
b. oR 1010 Lesh GARE RS eco x x 
U. woR4 5380 aiiaye 5 Feat beeeenod et ey, 
m. 4R 4041 feaeae x 
iD R 1011 Syne x Bate Ss a0 
. iQ 0112 pene: Wise at! Pek ges all Se 
Q. —2R 0221 Vahae x aK x 
Uv. —3R 0552 bNee x sow 
‘al —5R 0551 Shoe x Bay ANSE. 
2, —11R 0), ak, TI, ih PP Ne ee eeas, 3 xe 
M: Rit G4. Ul 3 me x 
IPs R5 3251 i x x 
Q: RS 9-7.16.2 ae x 
oO: R14 1513.33, 2 ay eee x ae 
te R16 17 SY 2 Bx Se 
p: —2R2 1341 x 
t: —2R4 3581 x x se8 
R: 4R3 Saal x x 
