Near Wilmington in New Castle County, Delaware — The American Northeast (Mid-Atlantic)
Iron Hill Iron Ore and Chert
sedimentary
Iron Hill iron ore and chert are sedimentary rocks formed by the erosion of iron and silica out of gabbro during ancient hot and human climatic conditions. At first glance, they look similarly, but the iron ore has softer minerals, looks duller and has rounded edges.
Iron ore actually consists of three different minerals:
red hematiteFractures in the rock also contain sparkly quartz crystals.
yellow limonite
black goethite
These iron ore and chert boulders were found on the south slope of Iron Hill near Iron Hill Museum. The iron ore at Iron Hill was mined in the 1700s and 1800s to make iron. Some of it was used to make cannonballs during the Revolutionary War. Chert was mined by Native Americans and used for tools and weapons.
Can you tell the difference between the iron ore and the chert?
Can you find the three different minerals in the iron ore?
Erected by Delaware Museum of Nature & Science.
Topics. This historical marker is listed in these topic lists: Indigenous Peoples and Communities • Industry & Commerce • Natural Features • War, US Revolutionary.
Location. 39° 47.957′ N,
this page online
Regionally, this marker is in Greater Philadelphia. It is also in the American Mid-Atlantic and on the Delmarva Peninsula. Globally, it is in the North Atlantic Region, North America, the Western Hemisphere, the Western World, and the Anglosphere. Historically, it finds itself in what was once New Netherland and also one of the original Thirteen Colonies.
Other nearby markers. At least 8 other markers are within walking distance of this marker: Brandywine Blue Gneiss and Barley Mill Gneiss (here, next to this marker); Gabbro (here, next to this marker); Cockeysville Marble (here, next to this marker); Sillimanite (a few steps from this marker); Pegmatite (a few steps from this marker); Weymouth Pine (within shouting distance of this marker); The Cottage (approx. 0.6
Credits. This page was last revised on April 30, 2025. It was originally submitted on April 30, 2025, by Devry Becker Jones of Washington, District of Columbia. This page has been viewed 106 times since then and 11 times this year. Photos: 1, 2. submitted on April 30, 2025, by Devry Becker Jones of Washington, District of Columbia.
