226 FIELD CoLUMBIAN MusEUM—GEOLOGY, VOL. I. 
disputed question as to whether the mineral crystallizes in the ortho- 
rhombic or monoclinic system. Owing, however, to the incomplete- 
ness of the crystals on account of their attachment, or to the stri- 
ations on the faces, only one reliable set of measurements bearing 
upon this point could be obtained. These were measurements of the 
zone ¢:x:x' sc’ =(001) : (201) : (201) : (oor), as already quoted. Com- 
pleting this zone by difference, the angles are: 
6% = (O01 je (20 =a7 1 hee 
eAvii—=(20T ti eon =O enon 
Me ue (201 eA OOl jeans ane oe 
| Thus the brachydiagonal is an axis of binary symmetry and the 
mineral must be regarded orthorhom- 
bic. Asnoted by Buszalso, the habit - 
of the crystals gives the impression of 
orthorhombic symmetry. 
The usual development of the 
crystals is shown in Fig. 3. Thath, 
shown in the direction of the brachy-} — 
diagonal is necessarily estimated, as 
no crystals doubly terminated in the 
direction of this axis werefound. The 
general resemblance in habit to that 
of cerussite from Rezbanya* figured Fic. 3—Caledonite. 
by Schrauf will be noted. 

GAY-LUSSITE. 

SWEETWATER VALLEY NEAR INDEPENDENCE ROCK, WYOMING. 
MUSEUM No. E 9698, 

On dissolving in water the native carbonate of soda found in the 
Sweetwater Valley, Wyoming, a residue of clay and minute crystals 
is left. Some of the latter were kindly forwarded to the writer by 
Prof. W. C. Knight of the University of Wyoming, who was the first 
to notice the crystals, so far as Iam aware. A test of the pyrognos- 
tic and crystallographic characters showed the crystals to be undoubt- 
edly gay-lussite. They are microscopic in size, none that I found 
being as large as the head of an ordinary pin. More exactly, none 
*Dana’s Mineralogy, p. 287. 
