146 FIELD COLUMBIAN MusEUuUM—GEOoLOoGY, VoL. III. 
23 mm. (7% in.) long in the direction of the macro-axis. All the 
crystals are bounded by the planes m (110), b (o10), 2 (111), and 
2’ (I11), although occasionally one of the sphenoids is absent. Some 
of the measurements taken with the reflecting goniometer on which 
these determinations were based are as follows: 
Observed Calculated 
b Am = (010) A (110) = 45° .35/ Pui Seid 
We Pet a a ETO) elo = 89°. 20’ 89° 26’ 
SAY 2 Seber UT) eet) = S23 alee, ei Gar 
Pah aeons Copia ae) GG) =e eae eis So o8, 
Recognition of the clinopinacoid b (o10) is made easy by the prom- 
inent cleavage in that direction. In the development of the crystals 
the prism m (110), and one of the sphenoids z 
(111) are most prominent, although the clino- 
pinacoid has in some of the crystals a width 
half as great as the prismatic faces. Occasion- 
ally, too, both of the sphenoids are found to be 
equally developed. An average development 
of the faces is shown in the accompanying 
figure (Fig. 3.) 
The crystals are simple individuals with 
the exception of two, each of which contains 
another individual implanted upon it, but 
not in any definite crystallographic direction. 
The crystals are all doubly terminated, but the 
Fic. 3. Epsomite. planes are frequently imperfect and cavities 
are numerous. When first received the crys- 
tals were colorless and transparent, but in the Museum laboratory 
they have deliquesced. 

LEADHILLITE 
SHULTZ, ARIZONA 
FIGS PLATESL 
A specimen of leadhillite from Shultz, Arizona, obtained from 
Maynard Bixby. (Mus. No. M 9604), in the form of a single, 
large, cuboidal crystal with fragments of other leadhillite crystals 
attached, seems sufficiently unlike other occurrences of the mineral 
to warrant description. The sides of the apparent cube of this speci- 
men have a length of 214 centimeters. One of its surfaces is yellow- 
