USGS Professional Paper 144 p 181-182


     The Allouez conglomerate (pl. 37) has been opened and mined at three widely separated localities - at Delaware, at Allouez, and at Franklin.


     The first production from this conglomerate was made by the Albany & Boston Co. in 1862 at the present Franklin Jr. mine. In 1882 the mine was sold to the Peninsula. Copper Co., which operated it till 1892. In 1895 it was sold to the Franklin Mining Co. The Pewabic lode was being mined for part of the period, and there is no accurate record of the total production from the Allouez conglomerate, but it was about 34,500,000 pounds. The average grade of the rock in the later period was between 11 and 12 pounds of copper to the ton.

     Work was begun on the conglomerate by the Allouez Mining Co. in 1869. From that time there was alternation of company operation and work by tributers till 1892, when production ceased. The production from the Allouez mine was total recorded production from 25,786,000 pounds. During the later part of the period the yield ranged from 13 to 19 pounds of copper to the ton of rock.

     From 1847 for many years the fissures and the conglomerate lode were worked at Delaware by different companies, usually in the most inefficient manner. Altogether a large amount of money was expended to little purpose. Mills were built near Delaware, and later a railroad was extended to Lac La Belle, where a mill was built. There is no accurate record of the production from the conglomerate separate from the fissures, but it is estimated at about 1,770,000 pounds. The largest output was made in 1883 and 1884, when the rock yielded from about 9 1/2 to 11 pounds of copper to the ton of rock. The recovery was poor, however, and the tailings probably contain as much or more than was recovered.


Mine Period Refined copper (pounds)
Franklin Jr.:
   Albany & Boston
1865-1882 865,057
   Peninsula 1883-1892 6,624,991
   Franklin 1901-1919 34, 473, 984
Allouez 1869-1892 25, 786,651
Delaware 1882-1885   1,770,570
    69,521, 253



     There has been no opportunity for the writers to examine the Allouez conglomerate as exposed in the mine workings. As seen on the dumps at all three localities it is a moderately coarse felsite conglomerate similar to the Calumet & Hecla conglomerate. From descriptions it appears that lenses of the Allouez conglomerate were well mineralized and some were rich but that much of it was poorly mineralized or barren.

     The character of the mineralization and of the rock alteration seems to be similar to that of the Calumet & Hecla conglomerate. A feature that is pronounced in the Allouez conglomerate at all three localities is the presence along joints and seams of many dark veins of calcite containing finely divided chalcocite. Similar veins are present on the margins of the Calumet & Hecla conglomerate ore shoot, as at Centennial, but are not common in the main shoot.


     The Allouez conglomerate has been opened at the Franklin Jr. mine by two shafts from the outcrop - in No. 1 to the twenty-fourth level and in No. 2 to the nineteenth level. The openings extend for about 2,500 feet along the strike, and within this area most of the ground has been stoped. The conglomerate has also been opened below the shaft workings by crosscuts from the Pewabic No. 1 shaft from the twenty-sixth to the thirty-seventh levels and here also for a maximum distance along the strike of about 2,500 feet, but the proportion of the ground stoped in this area is not so great. The stope map suggests that the main ore shoot in this area pitches south.


     A little shallow work was done on the Allouez conglomerate by the Rhode Island Co.


     A map in the report of the Commissioner of Mineral Statistics for 1882 gives developments on the Allouez conglomerate to January, 1883. Three shafts had been opened and the lode developed for a maximum distance along the strike of about 1,700 feet. No. 2 shaft extended to the fourteenth level.

     The production was derived mainly from a shoot lying north of a "slide" that reached the surface about 200 feet south of No. 1 shaft and intersected No. 2 shaft at the thirteenth level. The northern boundary of the shoot, which was mined for 700 to 1,000 feet north of the "slide," appears to have been indefinite.

     The mine produced as much copper after 1882 as it had before, but there is no map available showing the position and extent of the later openings.


     At Delaware the Allouez conglomerate has been opened by three main shafts and two shallow ones. No. 1 shaft extends to the ninth level, No. 2 to the tenth level, and No. 3 to the fifth level. The openings extend for a maximum distance along the strike of about 2,500 feet, but the main development has been confined to a distance of about 1,200 feet adjacent to No. 1 and No. 2 shafts. Only a small proportion of the lode within the developed area has been stoped.


     In the early operations in the Cliff mine considerable attention was given to the ninth amygdaloid or "floor," which was opened to the 90-fathom level and followed by drifts for short distances on most of the levels; on the 80-fathom level a drift was extended west about 500 feet and east about 400 feet. The early reports spoke favorably of the showing in these drifts, but in 1864 a test run showed the rock to average less than 15 pounds to the ton, and work was abandoned. In the report for 1864 it is stated that the copper content decreases away from the fissure. The thirteenth "floor" is also spoken of in the early reports as well mineralized, but very little work seems to have been done on it.

     When the mine was reopened in 1906 short drifts were run on amygdaloids in the south end of the mine. Whether all looked favorable or not is not evident. It is stated that some fair rock was taken, but the average was evidently poor. 

     Later some work was done on amygdaloids in the north end without encouraging results. Apparently no work was done at this time on the ninth and thirteenth "floors," which were regarded as most favorable in the early days.

   Collector's Corner     Previous section         Table of Contents                Next section