154 FIELD CoLUMBIAN MusEuM—GEo .oecy, VoL. III. 
were accordingly obtained as follows, the ratios of Washington and 
Phillips being given for comparison: 
C2020 = 0.055 7eu ale 0.69114, Farrington and Tillotson. 
ab C0. 0572 ~ a Ore Oar ies 
a3D 6 =0.90300 - tpe0 0 720 aV uaa ohare 
The total forms observed with the measured and calculated angles 
are as follows, new forms and fundamental measurements being 
marked with an asterisk: 
a (100) U CLO ty 
b (oro) 6 \(OFt} 
¢ (oot) *s (034) 
m (IIo) Te (Ogee 
Observed Calculated 
mvj m” = (110) A (110) = 8 yng oe 
Cerne. = (Ol 1) ern OnLy = *6g° 18’ 
a> Av. = (100) A (tor) = 535 59 haem 
Ch A/S 1) POLL awd a = 7. 5° | artes 
dA” Cd At O2 6 Nae mn Ore) = 32° 4b og oe 
No marked pleochroism of any of the crystals could be observed. 
On examination of some of the acicular forms with the polarizing 
microscope the usual characters were observed with the exception that 
a red variety occurred which does not seem to have been hitherto men- 
tioned. These crystals are characterized by a brownish-red color, 
occur in tufts, and the individuals average from .5 to 2 mm. in length. 
They are transparent and of marked brownish-red color but show 
little or no pleochroism. 
ORPIMENT | 
MERCUR, UTAH 
PLATES XLIV AND LIII 
Among the specimens obtained from Maynard Bixby, orpiment 
from Mercur, Utah, was represented by an especially notable one, 
(Mus. No. M 8206). This specimen consisted of a piece of limestone 
about 3x4 inches in size, upon which were implanted about fifteen 
large crystals of orpiment together with fragments of orpiment 
crystals and numerous crystals of calcite. The size and perfection 
of many of the orpiment crystals seem to exceed any that have 
