Robert Isaacs is best-known for his role in the discovery and development of the massive lead-zinc deposits in New Brunswick that became the cornerstone of Brunswick Mining and Smelting, now part of the vast Noranda organization. A talented mining engineer, he also had a hand in financing and developing many smaller producers, particularly in Newfoundland, where he developed a reputation for building mines with low capital and operating costs. His vision provided thousands of jobs in Eastern Canada.

Isaacs grew up in Thornbury, Ontario, on the shores of Georgian Bay. While still in high school, he began prospecting in northern Ontario with his brother. The boy prospectors made enough staking claims that Isaacs could afford to study mining engineering at University of Toronto.

After graduating in 1931, Isaacs joined Prospectors Airways, an exploration contractor. In the mid-1940s, while drilling in the Stull Lake region of Manitoba, he met James Boylen . The men soon formed a loose partnership, one that was to strengthen over the next 25 years. Isaacs' skills as an engineer and manager, combined with Boylen's flair for promoting and financing, enabled them to successfully develop ten mines in eastern Canada, the most important of which was Brunswick Mining and Smelting.

The Brunswick story began in 1952, when Isaacs caught wind of a report about lead-zinc mineralization found by a geology student at the old Drummond iron mine in New Brunswick. Intrigued, he called Boylen, who optioned the property for their account. Subsequent work led to the discovery of the No. 6 orebody, reported by The Northern Miner as the first massive sulphide deposit found in the Bathurst area.

In 1953, the No. 12 orebody was discovered and mine planning began in earnest. In the following years, Isaacs worked tirelessly to develop a mine, mill and smelter complex in the Bathurst area.

In 1955, he and Boylen founded Mindecon, which completed mine engineering and construction at Bathurst on time and under budget. Concentrates were shipped to Europe for processing, but in 1961 Isaacs incorporated a company to finance and build a smelter, and acid and fertilizer plants. In 1965, Noranda Mines bought the project for $65 million, using its financial and operating strengths to make the integrated mining and metallurgical business a success.

The efforts of Isaacs and Boylen at Brunswick did not go unnoticed by investors, who later supported their plans to develop other properties. Those were fruitful years for the partnership and for Newfoundland, where the pair conducted most of their work.

During the 1950s and 1960s, Isaacs and Boylen developed a 2,000-ton-per-day copper mine for Gulbridge Mines, followed by a similarly-sized copper operation at Tilt Cove for First Maritime Mining. They built an asbestos mine and a copper-zinc mine in the Baie Verte region and a copper mine and mill for Atlantic Coast Copper. In Quebec, they developed a zinc-silver mine at Bachelor Lake for Coniagas Mines.