The Mineral Resources of Greenland. 33 
The mineralogical changes with depth appear to be due to рге- 
glacial secondary enrichment. At the bottom of the mine the vein 
structure is as strong as at the surface, but the mineralized band narrows 
and copper values are practically absent. The mineralized portion of 
the vein at the surface probably carried over 4 % copper; at a depth 
of 40 m (131 feet) this fell to about 2 %, and at 64 m (210 feet) to 3/, %. 
Bornite and chalcopyrite occur from the surface to the bottom of the 
mine: chalcocite usually granular, in part sooty, practically disappears 
at a depth of 24m (79 feet). Below a depth of 42 m (138 feet) there 
appears to have been but little secondary enrichment of copper and 
gold, and below a depth of 14m (46 feet) of silver. Glacial erosion 
which certainly has removed more than 30 m (100 feet) and possibly 
150 m (500 feet) or more of rock, appears to have decapitated the pre- 
glacial secondarily enriched zone leaving only the lower portion, and 
post-glacial oxidation has been slight, although malachite and chryso- 
colla and probably the reported gold are of this origin. 
The chlorite schist in the vicinity of the mine contains a large 
number of irregular nodules formed after the schistosity developed. 
These consist of epidote, quartz and garnet and in some lenses also 
calcite and biotite. Bornite and less chalcopyrite and pyrite, and rarely 
alittle galena, (zinc blende is also reported) are also present. These sulphides 
are also sparsely disseminated in the schist and fill small fractures in it. 
The Josva copper ores were deposited by hot magmatic waters at 
presumably a very considerable and even great depth. Cupriferous 
pegmatites occur from 1.6—3.2 km (1 to 2 miles) west of the Josva 
mine, and very probably waters related to them formed the Josva 
vein. These pegmatite veins are from 5—45 cm (2 to 18 inches) thick, 
and consist predominantly of white quartz and pink felspar masses 
from 0.6—1.2 cm (1/, to 1/, inch) in diameter. A little biotite is present; 
purple fluorspar is quite common, and bornite and chalcopyrite with 
their derivatives chalcocite, malachite and chrysocolla, are intergrown 
with the other constituents of the pegmatite. The bornite and chalcopyr- 
ite occur in masses up to 1.2 em (1/, inch) in diameter. One of these 
cupriferous pegmatites examined microscopically consists largely of 
microcline with some secondary sericite, kaolin and epidote. Chloritized 
biotite, copper sulphide and fluorite, the latter in well defined crystals 
in felspar are also present. The copper sulphides occur as grains with 
one or more crystal faces developed. Some are wholly enclosed in felspar 
and others occur on the boundary of felspar grains. 
Other pegmatite veins consist of quartz, felspar, beryl, bornite, 
chalcopyrite and molybdenite. Certain minerals are common to both 
the Ivigtut cryolite and the Josva copper deposit, and they may be 
derivatives of the same and possibly a soda-syenite magma. 
LXTIT. 3 
