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It makes a very handsome specimen for the cabinet, and should be carefully trimmed to show the characteristics of the mineral. Datholite. This mineral has been found very frequently in the tunnel, it occurring in pockets in the softer trap near the chlorite, and also in the latter, generally at a depth of one hundred and fifty feet from the surface, and consequently near the ceiling of the tunnel.
The quartz grains show secondary growth. 13 Altered Gabbro Thirty-two Miles Above Wuchusk Nipi on Nascaupee River. A coarse dark green rock whose principal constituents are pyroxene plagioclase and magnetite. There is a slightly developed diabasic structure and the rock is much altered by weathering; the resultant product being chlorite. 14 Quartizite Bibiquagin Lake.
With respect to occurrence, the older sandy and clay slates, chlorite slates, micaceous, and hornblendic schists, particularly at or near their junction with the intrusive granite and diorite, generally form the most likely geological country for the finding of mineral lodes, particularly gold, silver and tin.
There can be no doubt in these cases that strata once composed of mud, sand, and gravel, or of clay, marl, and shelly limestone, have for the distance of several yards, and in some instances several hundred feet, been turned into gneiss, mica-schist, hornblende-schist, chlorite- schist, quartz rock, statuary marble, and the rest.
In general, the greater number of the specimens which are to be found in the tunnel occur in veins generally perpendicular, and with other minerals of little or no value, as calcite, chlorite, and imperfect crystals of the same mineral. A few occur in nodules inclosed in the solid body of rock, and in which condition they are seldom of value.
Structurally, therefore, these isles are a continuation of Land's End, but the granite has become less consistent and more friable; it is largely broken into felspar, quartz, and mica, with schorl, chlorite, and hornblende.
There is no such uniformity of strike as to give to the rivers a zig-zag course of any regularity, or one having any apparent dependence on a prevailing arrangement of the rocks; for, though the strike of the chlorite and clay-slate at elevations below 6000 feet along its course, is certainly north-west, with a dip to north-east, the flexures of the river, as projected on the map, deviate very widely from these directions.
The rocks and peaks of Mainom are said to overhang the descent here with grandeur; but the continued rain hid everything but a curious shivered peak, apparently of chlorite schist, which was close by, and reflected a green colour it is of course reported to be of turquoise, and inaccessible.
It is not uncommon to meet with an argillaceous rock having the same composition, without the slaty cleavage, which may be called argillite. CHLORITE SCHIST is a green slaty rock, in which chlorite is abundant in foliated plates, usually blended with minute grains of quartz, or sometimes with feldspar or mica; often associated with, and graduating into, gneiss and clay- slate.
The rock formation of the hills upon its right continued of that chlorite schist which prevailed near Mr. Whaby's, which I have already noticed, and quartz still appeared in large masses, on the loftier ranges opposite, so that the geology of the neighbourhood could not be said to have undergone any material change.
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