The historical gold mining activity in Quebec is related to the works of alluvions and veins. The auriferous alluvions of the older Lower Canada covered and extended region. In 1852, the Geological Commission reported the occurrence of gold over more than 10,000 square miles. The gravels through which gold was irregularly distributed were covered by a layer of vegetable earth, and often by a bed of clay. They reposed in art upon metamorphic Lower Silurian rocks consisting of schists, generally talcose, micaceous or chloritic associated with diorites and serpentines. But to the southward, these Lower Silurian strata were overlaid by others of Upper Silurian age, which were covered by gold-bearing alluvions. These rocks consist of argillaceous schists with sandstones and limestone, all more or less altered.
Many of the gold seekers in the Chaudiere Valley considered an analogy between the auriferous alluvions and those of California. Alluvial gold was profitable sought for in the Chaudiere River itself, at its junctions with several rapid tributary streams. But it is at the Devil’s Rapids where the Chaudiere makes a sharp turn and runs west-south-west that gold was abundantly found in the cavities, fissures and cracks of the clay-slates, which often form the bed, both of this river and its tributaries were running in the direction mentioned, forming parallel ridges which were uncovered in low water; at which times the country people was able to break up and search these slaty rocks to the depth of several meters. The fissures of these rocks were filled with clayey gravel in which gold was met with. In one of these bands of slate, which the country people called veins, the gold was tarnished by a black earthy coating of manganese oxide. This deposit of alluvial gold occupied a distance of about 1.6 km of the river’s bed and was situated below the gold bearing quartz vein, and which was known as the O’Farrell vein.
At the Devil’s Rapids, an excavation on the right bank and about 6 m distant from and below the Kennebec road was opened, having the slate rock its floor and continued for 60 m in hard alluvial conglomerate cemented by clay. Gold was also found in many places in the bed of the Chaudiere at low water. Up to 1866, the Gilbert or Touffe-des-Pins River was the scene of important works, and yielded the largest amount of gold. In ascending this stream, which is a torrent at certain seasons, was easily prospected during the dry summer and found the remains of working undertaken 16 years before. A company of miners took up this old working in 1866, but their explorations were not long continued, notwithstanding certain satisfactory results, among which may be mentioned a nugget of 6 oz.weight.
On the concession De Lery a rich deposits of gold was found. An excavation determined the limits of the rectangular deposit and was carried to the bed rock, a depth of 2.5 m. Three distant layers were met: first, 0.30 m of sandy vegetal oil; second, a yellowish sand with pebbles; third, a clayey gravel containing gold, the latter layers had each a thickness of 0.90 m. the washing by means of a rocker yielded a limited gold of gold, the greater part was extracted from the fissures of the sandstone that formed the bed.
About the gold veins, some of these were free from foreign minerals, while other contained sulphides such as pyrite, arsenopyrite, blende and galena. The reports of several surveys showed the presence of native gold in the veins belonging to the crystalline schists of the Lower Silurian near Sherbrooke, in Leeds, and in St. Sylvester in St. Giles, and in those traversing the Upper Silurian rocks in Aubert-Gallion, and in that of Vaudreuil at the Devil’s Rapids in the Chaudiere. While establishing the presence of gold in the veins of the upper and lower formations, both might have contributed to the auriferous alluvions.
Although the veins attracting most attention are in Vaudreuil, numbers of similar quartz veins were found all the way southward to the frontier, and many were discovered in Aubin-Delisle and Aubert-Gallion, and in the townships of Jersey, Marlow, Liniere and Metgermette. Several outcrops of quartz appeared along the Kennebec road; and at low water, and some of them were seen in the beds of the Famine, Du Loup, and their tributary streams, such as the Oliva, the Metgermette and others. Gold was discovered in Marmorra in 1865, as free gold in quartz and mispickel.