Franklin, known as the Fluorescent Mineral Capital of the World, is located over a rich ore body containing more than 150 minerals, many of them fluorescent and 25 of which are found no where else on earth. Settled in the 1600s, the village known as Franklin Furnace developed near iron mines and iron smelting operations located along the Wallkill River. In the early 1800s zinc deposits in the area began to be developed commercially. For most of the century many small companies mined zinc and iron in the Franklin area. In 1897 all zinc mining efforts merged into the New Jersey Zinc Company. The Zinc company was a major controlling factor in the development of Franklin. Immigrants from Russia, England, Hungary and Poland joined the work force at the mine. The population, 500 in 1897, swelled to 3000 by 1913 when the area incorporated as the Borough of Franklin.

In the early 1900's, the village of Franklin Furnace had grown and spread from the pond area to the Main Street area. Since Hardyston Township was mostly rural and agricultural and the village of Franklin Furnace had discovered the wealth of the minerals in their community, application was made to the N.J. Legislature for the passage of an act to separate from the township of Hardyston. Upon passage of the bill on March 18, 1913, and ratification by the citizens of Franklin in a special election on May 15, 1913, the Borough of Franklin officially came into being, with the selection of David W. McCarthy as it's first Mayor.

The New Jersey Zinc Company was the largest employer in Sussex County and paid one third of property taxes in Sussex County, providing steady employment for many people. Franklin in the 1930's was virtually untouched by the depression, providing a four day work week for the N.J. Zinc Company employees. For all of these reasons, the Borough of Franklin was designated as the "Model Mining Town of the East", and the Fluorescent Mineral Capital of the World.