94 IRON ORES OF IRON SPRINGS DISTRICT, UTAH. 
spicuous place. Iron-ore deposits have been included in this class 
largely because of the classic work of Vogt on the Christiania deposits. 
Individual deposits of western contact iron ores have not been spe- 
cifically referred to this class because they have not been sufficiently 
known. The pneumatolytic origin of the Iron Springs ores now 
seems to be sufficiently well based and their similarity to other 
western contact iron ores sufficiently close to make it possible to 
assign a pneumatolytic origin to this general class of ores with some 
confidence. 
The direct development of magnetite in pegmatitic veins is de- 
scribed by Spurr in the Georgetown quadrangle of Colorado. The 
case is conclusive, for magnetite crystals of considerable size are 
found in the interior of unaltered pegmatite veins. 
Spencer reached the conclusion that certain of the New Jersey 
magnetites are essentially pegmatitic in their origin. In addition to 
the Christiana deposits, Vogt 6 cites other European deposits c which 
he regards as of the same origin. Beck d does the same. Of interest 
also in this connection is the recent work of Stutzer e on the ores, 
which he regards as dikes, of the Kirunavaara and Luossavaara dis- 
tricts in northern Sweden, and the still more recent work of Sjo- 
gren / on the Scandinavian iron ores. 
The prevalence of an iron cap or gossan above sulphide deposits 
in fissure veins or along the contact of igneous rocks and limestones 
is responsible for a widespread view that western iron ores of this 
occurrence will be found to grade down into sulphides; that the ores 
are the oxidized portions of sulphide veins which may have originated 
in the manner here outlined for the Iron Springs district; that the 
ores therefore have an ultimate igneous source to the same extent 
as the sulphide deposits, whatever this may be. Reasons are given 
on another page for the belief that the Iron Springs magnetite was 
deposited directly from hot solutions and not as an alteration prod- 
uct of sulphide, but that simultaneously there were deposited small 
and variable amounts of pyrite. So far as the writers know, there is 
no evidence of increase in sulphur content in depth in any of the ores 
of this class in the localities cited, beyond perhaps the first few inches 
or few feet, from which the sulphide, originally deposited with the 
a Spencer, A. C, Genesis of the magnetite deposits in Sussex county, N. J.: Min. Mag., vol. 10, 1904, 
pp. 377-381. 
b Vogt, J. H. L., Problems in the geology of ore deposits: Trans. Am. Inst. Min. Eng., vol. 31, 1902, 
pp. 125-169. 
c Northern Sweden, Kristiania district, southern Hungary, Island of Elba and Dieletti, France. 
d Beck, Richard, The nature of ore deposits, translated by W. H. Weed, 2 vols., New York, 1905, 
685 pp. 
< Stutzer, O., Die Eisenerzlagerstatte Gellivare in Nordschweden: Zeitschr. fiir prakt. Geol.,bd. 14, 
No. 5, May, 1906, pp. 137-140; Die Eisenerzlagerstattenbei Kiruna: Zeitschr. prakt. Geol., bd. 14, No. 3, 
March, 1906, pp. 65-71. 
/Sjogren, Hjalmar, The geological relations of the Scandinavian iron ores: Trans. Am. Inst. Min. 
Eng., vol. 38, 1908, pp. 877-946. 
