[16 ECONOMIC GEOLOGY 
pp. 95-285), by T. C. Phemister (Ign. Rocks, Sudbury, Ontario 
Dept. of Mines, xxxiv, 1926, pp. 1-61), and Jas. Park (Econ. 
Geol., xx, 1925, p. 504). They point out that in addition to 
the sulphides having been formed after the silicates, the 
majority of the ore bodies are not in the gabbro, though near 
it, that the ores were introduced long after the intrusion 
of the gabbro, and that they occur in the sedimentary as 
well as in the igneous rocks. Phemister has shown that 
the micropegmatite altered both the overlying Trout Lake 
Conglomerate and the underlying gabbro, and that the 
most basic part of the gabbro is not at its lower side, as 
required by the igneous theory of the ore, but near the top. 
The igneous formation of the ore rests on the claim that it 
occurs within the basic rock. Yet of the marginal ore-bodies, 
the lower part of the largest, the Creighton, is wholly within 
the granite, which was itself intrusive into the gabbro and 
was followed by the intrusion of quartz-diorite dykes; and 
the ores were deposited later than these dykes, and are 
only associated with the gabbro along its shattered margin. 
The upper part of the Crean Hill ore-body is in granite and 
the lower part is along the contact between that rock and 
gabbro. The Victoria Mine occurs near the edge of the 
gabbro, but the ore is entirely in greenstone and quartzite (Fig. 
36). The Levack Mine is in gneiss. The Garson Mine consists 
of parallel veins of ore in greenstone and schist, and partly 
along the contact between gabbro and greenstone. Of the 
off-set beds the famous deposit at Copper Cliff is a kind of 
pipe-lode and, according to Phemister, is an altered shattered 
quartz-diorite, of the same age as the last intrusions at the 
Creighton Mine; it has been cemented to a breccia by the 
sulphides. The Worthington Mine is in similar rock that 
has been sheared and impregnated by ore. The Frood 
Mine is also a sheared brecciated band along a fault, and the 
ore in it occurs in all the rocks, igneous and sedimentary, 
traversed by the fault. In the Murray Mine the ore is the 
cement to blocks of gabbro. 
The field evidence agrees therefore as to the formation of 
the ores with their microscopic structure. After the deposi- 
tion of the sedimentary Animikie rocks the country was 
invaded by a sheet of gabbro, which was followed by an 
intrusion of micro-pegmatite, the junction, as pointed out