362 
MINERALOGY: LARSEN AND WELLS 
Analyses of gearksutite 
1* 
2 
3 
4 
Al 
15.11 
15.37 
15.20 
15.1 
Fe 
tr. 
0.30 
Ca 
22.41 
21.02 
22.30 
22.4 
Mg 
tr. 
0.16 
Na 
0.04 
1.06 
0.10 
K 
0.07 
0.23 
0.04 
CI 
0.20 
F 
41.00 
41.81 
42.07 
42.9 
0 
5.09 
4.82 
4.83 
4.5 
H2O- 
0.44 
H2O+ 
15.20 
15.03 
15.46 
15.1 
99.36 
100.00 
100.00 
100.0 
* Si02 none, AI2O3 28.49, Fe203 tr., CaO 31.37, MgO tr., Na20 .05, K2O .08, F 41.00, 
H2O- .44, H2O+ 15.20, less O for F 17.27, total 99.36. 
Although the direct determination of fluorine, in which the fluorine 
was weighed as CaF2, yielded 41.0 per cent in Analysis 1, no great accu- 
racy is claimed for this determination. The agreement of the other 
constituents in the three analyses, however, shows the practical identity 
of the minerals, the chief difference being that a small amount of Ca is 
replaced by Na in the Greenland mineral. All four analyses agree very 
well with the formula CaFgAl (F,OH)3.H20. with F: OH = 2: 1. 
Heretofore gearksutite has been described only as an alteration prod- 
uct of cryolite, but at Wagon Wheel Gap no cryohte has been recognized 
and the gearksutite is believed to have been formed by a metasomatic 
alteration of the rhyolitic wall rock much as kaolinite or sericite is 
formed. Indeed, on the first visit to the deposits the gearksutite was 
mistaken for kaolinite. It seems probable that the gearksutite was 
developed in the wall rock by the ascending hot solutions which de- 
posited the fluorite in the vein. 
Creedite, a New Mineral. — ^A specimen collected from the dump of one 
of the upper workings of the fluorite mine proved to be made up in 
large part of a new mineral. The name 'Creedite' is proposed for this 
mineral from its occurrence near the center of the Creede quadrangle 
of the United States Geological Survey. 
Creedite makes up about two-thirds of the specimen and is in white 
to colorless grains and poorly developed crystals up to 5 millimeters 
across, imbedded in a dull white kaoKnite, with a very Kttle barite. The 
kaolinite is believed to be derived from the alteration of some unknown 
mineral. 
Creedite is nearly colorless, has a hardness of about 3 J, intumesces 
before the blow pipe, showing the calcium flame, and finally fuses to a 
