20 Sypney Н. BALL: 
were snowy white and opaque and pitted by round depressions and 
were porous like rotten ice. Portions were dissolved along the numerous 
cleavage planes, the mineral then closely resembling highly weathered 
calcite. The associated siderite is partially altered to limonite, which 
stains the surrounding cryolite. Along major fractures limonite occurs 
even to the bottom of the open cut. Mineralogists report as alteration 
products of cryolite, pachnolite, thomsenolite, ralstonite, gearksutite, 
ФР. of NW. 
Arsuk fiord 
< 
EN 
1 
| 
| 
| 
\ 
< 
SSS ge 
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Cryofrte 
Cross-section of Cryolite pit.near North end. 
(Surface after Tayler) 
Approximate scale 
50" 100 
| Coane em PT Е 
Fig. 7. 
arksutite, hagemanite and ivigtite. Apparently from GIESECKE’s des- 
cription, some sulphur was formed by the weathering of the galena of 
the deposit. 
The predominant rock in the vicinity of Ivigtut is granite gneiss, 
which includes numerous large and small masses of hornblende gneiss, 
once a diorite. This supposedly pre-Cambrian gneissic complex is cut 
by numerous younger dikes of diabase, presumably of Paleozoic or 
Mesozoic age. The gneissic planes strike N.E.—S.W. and dip 45° S. 
of E. At the mine a small lenticular body of pink granite intrudes the 
gneisses parallel to the gneissic structure. It is slightly porphyritic and 
rather mica-poor. Presumably this is older than the diabase, as is the 
