The first activity unique to Iron Hill was the quarrying of stone called jasper by the Native Americans. Found in quantity only on Iron Hill it was an exceptional material for the fashioning of projectile points. Remnants of work areas displaying large amounts of jasper flakes have given archeologists much valuable information about the earliest inhabitants. The Iron Hill Museum, located in the old Iron Hill schoolhouse, has a wealth of information on Lenni Lenape culture and the geology of the region.

First mentioned as 'Yron Hill' on Augustine Herman's map published in 1672, the name bears witness to the existence of iron ore on the site. Except for a report, with many different versions, of three or four travelers meeting their demise at the hands of hostile Indians in the late 1600s while crossing the hill, the giant slept on. In 1701a group of Welsh immigrants, organized as a religious group in Wales, petitioned for and received a grant of 30,000 acres in what later became Pencader. The land, which surrounded Iron Hill and extended into part of Cecil County, was granted to three Welsh leaders and they in turn sold plots of land to other Welsh settlers. Iron mining was a familiar occupation in Wales and evidence that these early settlers were not unaware of the local iron ore deposits appeared during later years. The open pit method was then being used and a tunnel made by earlier Welsh miners was uncovered, complete with rusted shovel and tallow candle.

The early mining efforts were abandoned and the hill, its trees sacrificed for the production of charcoal to fuel iron furnaces, was once more left to the wildlife. The next important visitors would be Generals Washington, Lafayette and Greene reconnoitering for British troop movement before the battle of Cooch's Bridge in 1777. A seven-hour engagement would later take place covering the entire hill and surrounding area. Many lives were lost and soldiers were buried by local folk where they fell, in unmarked graves. How many soldiers sleep on Iron Hill only the mountain knows.

In 1781 Lafayette and 1500 troops landed at Christiana Bridge. They may well have passed in the shadow of Iron Hill on the Old Baltimore Pike, the most direct route to the Chesapeake Bay, in pursuit of Benedict Arnold who was plundering Richmond, Virginia.

During all these years, one buyer after another purchased parts of Iron Hill hoping to make a fortune from the ore. J.P. Whitaker, owner of Principio Furnace in Cecil County was the last of a long line of owners to mine the hill, ceasing operations in 1884 when the ore ran out. On nearby Chestnut Hill, William McConaughey followed suit from 1873 to 1884. The Chestnut Hill site came perilously close to being lost when developers claimed the area with its spectacular views for a housing development.

Both Iron Hill and Chestnut Hill ore pits are now protected and this era in Delaware iron manufacturing will continue to be researched and preserved for future generations.