Postcard photo of the O’Brien Mine site, Cobalt Northern Ontario, Canada.
‘Douglas Ford Printer, Toronto.’
Postmarked ‘Jun 22-08’ from Cobalt ON to Detroit MI. Postage stamp removed.
Slight staining left side of front.
This mine was the longest continuously operating mine in the Cobalt area (1905-1967). It was developed through 5 shafts, the deepest being 345ft; and over 16 miles of drifts, cross-cuts, and raises. Total production was approx. 41 million oz. Ag; 3 million lbs. Co; 200,000 lbs. Ni; 500,000 lbs. Cu; and 64 oz. of gold.
The Cobalt silver rush started in 1903 when huge veins of silver were discovered by workers on the Temiskaming and Northern Ontario Railway (T&NO) near the Mile 103 post. By 1905 a full-scale silver rush was underway, and the town of Cobalt, Ontario sprang up to serve as its hub. By 1908 Cobalt produced 9% of the world's silver, and in 1911 produced 31,507,791 ounces of silver. However, the good ore ran out fairly rapidly, and most of the mines were closed by the 1930s. There were several small revivals over the years, notably in World War II and again in the 1950s, but both petered out and today there is no active mining in the area. In total, the Cobalt area mines produced 460 million ounces of silver.
The Cobalt Rush was instrumental in opening northern Ontario for mineral exploration. Prospectors fanned out from Cobalt, and soon caused the nearby Porcupine Gold Rush in 1909, and the Kirkland Lake Gold Rush of 1912. Much of the settlement in northern Ontario outside the Clay Belt owes its existence indirectly to the Cobalt Rush.