Old mines given new life with advent of diamond drill

Graham Jaehnig

Last week, we talked about the significance of the diamond drill in re-initiating mining production on copper properties previously thought to be worthless or mined out. Not only was diamond drilling instrumental in 20th century ventures in the Ontonagon region, as we talked about last week, but it was equally instrumental in developing new mines in northern Houghton and southern Keweenaw counties.

The State of Michigan Geological and Biological Survey, Publication 13 for 1912, reported that diamond drilling was carried on by more companies than in 1911, and was particularly successful at the Mayflower and Old Colony properties.

“A number of remarkable cores were obtained from the Mayflower lode and the companies have good reason to believe that they have found an ore body that will be a large producer,” wrote Reginald E. Hore of the Michigan College of Mines in the geological report. “Drilling is being continued to further define the lode and the structural conditions before sinking a shaft.”

In that statement, Hore mentioned, almost as an afterthought, the importance of the diamond drill in economically exploring potential properties, in this case, of the Mayflower and Old Colony ventures. Core samples obtained from the drilling suggested the existence of a large ore body. But the drill also allowed for further sampling to ensure the deposit was worth sinking a shaft, before investment capital was expended on development.

During the same year the Naumkeag Copper Company had two drills working their property southwest of Houghton, which the company was incorporated to develop. The drill was not limited to surface work, however, and proved a huge advantage underground, as well.

Several mines used diamond drills underground in 1912, Hore reported, and there was a tendency to give increased attention to the probing of foot and hanging walls by diamond drilling at frequent intervals.

“Much ore has been found in this way,” he stated, adding that at some mines drills were kept in constant service on this work “and very satisfactory results are obtained”.

During 1912, very satisfactory results were obtained at South Kearsarge mine from test drilling in the footwall, and the company’s geologists felt optimistic that some other parts of the Kearsarge lode would show similar deposits, Hore reported.

Diamond drilling created very positive results, to be sure, which encouraged a great deal of optimism. But companies frequently conducted additional and varied studies, compiled data and results, and from that, were able to know the mineral content of the mines, the lodes, and know where the companies stood. For example, close and accurate production reports told companies what their yearly production of ore was, how it compared to previous years, and even accounted for any increases or decreases in production.

Production records for 1912, for example, showed a falling off on the part of some of the larger producers, along with substantial increases by a few. The falling off was partly due to diminished values per ton and partly to decrease in tonnage, Hore reported.

“The decreased production resulted, in some mines, from ordinary stoping in poorer parts of the lode,” Hore wrote, “but in other cases it was partly to be charged against changes in methods of mining, which necessitated much dead work.”

The necessity of “dead work” was in most instances, mining companies transitioning from the advancing method of mining to the retreating system, which we will talk about next week.

“The tonnage was in nearly all cases less than would have been mined if there had been sufficient men available,” Hore stated in his report. There is reason to question that assertion, however.

In its Summary of the Operations of the Calumet and Hecla (C&H) Mining Company for the fiscal year ending in April, 1904, the directors stated that the new openings on the conglomerate lode in the vicinity of the Red Jacket Shaft had continued to be unsatisfactory.

“Rock mined in that district shows a decrease of about 15 percent in copper from former years,” Alexander Agassiz, company president wrote in his report.

Agassiz went on to state that all exploration work in the No. 12 Shaft on the Hecla Branch (the southern most shaft) had been discontinued, and the work of removing the shaft pillars of the No. 11 Hecla Shaft had begun, because “no ground of any value having been developed by the deepest openings of the shaft.”

In the fall of 1903, the company began opening the Kearsarge Amygdaloid lode. Locations for three shafts were determined. The most northerly shaft was sunk on a vein and drifted a short distance, and the summary report stated that the “quality of the rock encountered was fair.”

Two years later, the Summary of Operations ending in the year 1906, mentioned the continuation of removing the pillars from the No. 11 Hecla “preparatory to abandoning that shaft, and have also continued to take out the pillars of Nos. 2 and 3 Hecla.” Shaft pillars were removed from the bottom of the mine upward to extract the available copper from them.

In an attempt to maintain high copper production, C&H began to look away from the southern end (Hecla Branch) of the Calumet Conglomerate Lode and more toward developmental work on the Osceola prospects.

“We have derived a substantial addition to our ingot product and are now producing about 6 (million) pounds per year from the Osceola Lode,” the report stated. “We are stamping about 1,000 tons of rock a day from this lode and intend to increase this tonnage as fast as practicable.”

C&H directors also began looking at old, abandoned mines as possible means for maintaining its past production levels.

The 1906 summary report stated that under a recently passed Michigan law, C&H could now “subscribe for, purchase and be interested in the stock of any other company formed for mining, smelting or manufacturing wholly or at any place other than the state of Michigan.”

With the law in place, C&H stockholders authorized the company’s directors to organize the Manitou Mining Company (formerly the Delaware Mining Company), of which C&H owned nine-tenths of the stock. C&H also organized the Frontenac Mining Company to hold the mineral and other lands the company had purchased from the Central Mining Company, as well as the Manice lands and other tracts in Keweenaw County.

In its initial exploration work, the report stated that C&H was relying on diamond drills on parts of the Frontenac and Manitou properties, while on the Manitou, they also included drifting to more accurately determine copper content.

“On the Delaware property (now Manitou) we are drifting from the bottom of a shaft 100 feet deep on the Montreal amygdaloid,” the report said. “The showing of copper in this vein is fair.”

Through extensive diamond drilling and other exploration types, C&H located the Calumet Conglomerate, Osceola Amygdaloid, and the Kearsarge Conglomerate lodes on the former Delaware property. The company also possessed options for the purpose of other mines, including the New Jersey, the Nonsuch (in Ontonagon County), along with control of the Superior, Caldwell, Superior, Gratiot, and other properties. Money for these operations came from the establishment of the “Development and Equipment Fund

“The purchase of some of these properties has given us a large supply of timber,” the summary stated, “and we hope in time to find producing mines which may materially add to the output of the Calumet and Hecla proper.”

The summary report for the following year, 1907, stated that just under $185,000 of the fund had been expended on exploration and development of the Manitou, Gratiot, New Jersey and Superior Mining companies, the Frontenac and Superior Copper companies, along with Nonesuch Mine, and Dana and Manice Lands.

In all of these prospects, explorations and ventures, C&H relied heavily on the technology of diamond drilling and would continue with diamond drilling practices well into the 1960s. Core samples taken from diamond drilling areas offered two suggestions: A. the area contained enough copper to warrant development, or B. It did not.


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