(...continued) Not until July 1847, did the Andover Mine reemerge from abandonment when it when was reopened by the Trenton Iron Company, spearheaded by industrialist proprietors Peter Cooper and Abram Hewitt.
Cooper and Hewitt's influence resulted in the construction of the Sussex Mine Railroad chartered on March 9, 1848. The mule drawn railway was used to transport ore from the mine to the Morris Canal and then to the Thomas Iron Furnaces in Allentown, PA. This railroad was later upgraded signficantly and renamed the Sussex Railroad, which provided more efficient transport.
From 1851 to 1853, the mine produced approximately 3,000 tons per month. Its ore, which was high in manganese content, was highly desirable as this provided added strength when milled into rails and wire. Production decreased by the early 1860's as the ore started reaching depletion. Unlike most Highlands magnetite deposits, most of which were never bottomed, the supply at Andover was unique in that it was finite. Consequently in 1863, the mine was again abandoned.