126 GEOLOGY AND GOLD DEPOSITS OF THE CRIPPLE CREEK DISTRICT. 
extremely delicate white fibers of very feeble, double refraction and an extinction 
which is probably parallel to the principal sections of the nicols. An analysis by 
W. T. Schaller of a very small quantity gave: 
Analysis of basic 
SrO. 25. 1 
CaO. 15. 1 
A1 2 0 3 . 13. 9 
MgO. 2. 5 
S0 3 . 13. 9 
strontium sulphate. 
H 2 0 (107° C.).None. 
H 2 0 (red heat). 24. 1 
94.6 
At 260°, 1.49 per cent H 2 0 was driven off, while the rest remained until red heat. 
Repeated determinations gave the same result. The analyzed material was homo¬ 
geneous. The composition is that of hydrous basic sulphate, corresponding perhaps 
roughly to CaO, SrO, A1 2 0 3 , S0 3 , 5 H,0. This is the first hydrous strontium mineral 
known to mineralogy, and as soon as its composition is satisfactorily ascertained it 
will be established as a new mineral species. 
Ghalcanthite .—Occurs very sparingly in the oxidized zone of the veins. Penrose 
mentions it from the Gold King mine in Poverty Gulch. It also occurs in the Lone 
Jack vein, Ophelia tunnel, and at several places in the Chicago and Cripple Creek 
tunnel. 
Mirabilite .—Delicate efflorescences of hydrated sodic sulphate are very com¬ 
mon in old drifts within the oxidized zone. Usually a little potassic sulphate is also 
present. It has been identified from the Anaconda-Raven tunnel and from the 
Last Dollar mine. 
Mallardite .—Efflorescences of this mineral, which is a sulphate of manganese 
with 7 molecules of water, were collected from the Moon-Anchor mine and deter¬ 
mined by Hillebrand. It contains also 2.55 per cent MgO and a very small amount 
of nickel. 
Epsomite .—Hydrated magnesium sulphate was identified from the 1,000-foot 
level of the Portland mine, but mixed with it are also some sulphates of manganese 
and alkalies. 
Other sulphates .—In the drift on the Lone Jack vein in the Ophelia tunnel, a nar¬ 
row vein in granite, the walls are coated by a white, silky, fibrous substance, which 
was determined by Hillebrand to be a mixture of hydrous sulphates of aluminum, 
zinc, ferrous iron, and magnesium. It contains no lime. Coatings of a somewhat 
similar but more massive substance of pink color proved to contain in addition a not¬ 
able amount of cobalt sulphate, to which the color of the mineral is doubtless due. 
Apatite .—Occurs commonly in the latite-phonolites as stout prisms up to 4 mm. 
long and showing prism, basal plane, and pyramid. Regarding its inclusions see 
page 74. It is also abundant as a secondary mineral in slender microscopic prisms 
with adularia in the Elkton mine. 
1 Yavellite .—A white phosphate in spherical masses of radial structure, probably 
wavellite, is mentioned by Penrose from the veins of the Raven and Bertha B. mines. 
The same mineral was found in the May mine, Arequa Gulch, and at a prospect one- 
eighth of a mile northeast of Midway station. Small amounts of phosphates mixed 
in the sulphates and various ferric silicates have been noted by Hillebrand in oxi¬ 
dized products from the Vindicator and Portland mines. 
