This Was Then: Iron Mines

Island bog iron on Old Ironsides?

Elements from Crevecoeur's 1782 “Map of the Island of Martha’s Vineyard”. Other highlights on the map include (4) “Dr. Mahew’s house”, (7) “The best mowing grounds in the island, yielding four tons of black grass per acre”, and (9) “A mine of good pipe-clay.” — St. John de Crèvecoeur, J. Hect

French-American writer and cartographer Jean de Crèvecœur, in his popular 1782 book, “Letters from an American Farmer,” described the Island of Martha’s Vineyard to a European audience in a lengthy chapter. He praised Edgartown for its seaport, Chilmark for its pastures, Tisbury for its timber and its harbor, and Gay Head for its colorful ochres with which the inhabitants painted their houses. He included a fold-out map of the Vineyard, identifying the various sheep pastures, herring brooks, salt meadows, woodlands, and peat swamps, as well as “The Great Beach against which the Sea continually beats” (South Beach). But he also identified nine specific points of interest, including a curious one near the highlands of Chilmark — an “Iron-mine, the ore of which is carried to the forges at Taunton.”

Iron is found naturally on the Vineyard in many forms. The ochre extracted from clay is pigmented with iron oxide, and was traditionally used in red, yellow, and orange paints not only for colonial homes but also for Wampanoag bodies. While iron smelting was not among Native Americans’ many skills, they were quick to adopt European iron and steel. (The day explorer Bartholomew Gosnold first arrived in America in 1602, he was met by “eight Indians in a Basque-shallop with mast and sail,” one of whom held an iron grapple.) Iron was one of the first resources sought by the colonists, as they needed it to manufacture nails, and the first iron smelters were built outside of Boston in 1644. Vineyard colonists, too, needed iron, and they quickly found some.

Iron ore was not mined from some Vineyard quarry — it was actually harvested from its wetlands. “Bog iron” is found at the bottom of freshwater swamps in reddish, porous, heavy lumps. Formed mostly by iron-fixing anaerobic bacteria, it’s a renewable resource. Bog iron will grow back to harvestable quantities in 20 years or so. Author Joseph Chase Allen told of Vineyard blacksmiths producing ”the finest knives and tool-blades, oxchains, crow-bars and many other items from bar-iron. The ore came from the Vineyard’s own bog-iron pits.”

Bog iron was critical to the Island’s decimated economy after Grey’s Raid in September 1778. Historian Charles Banks wrote that during the bleak winter that followed, Vineyarders “managed to get a scanty supply [of fuel] from the mainland, by exchanging iron or bog ore, as it is called, which, by running the gauntlet of the British cruisers, was transported to Wareham to be smelted. At one time a boat loaded with this bog ore was captured, while crossing the sound, by a British cruiser; the men in the boat pleaded poverty, saying they were taking this ore to be smelted and cast into pots and kettles, as General Grey’s army had taken about all there were on the island. So plausibly did they set forth their condition and so eloquently did they plead their cause, that the British commander was moved to compassion, ordered their release, and the boat and cargo being restored to them, they went on their way rejoicing. This very ore was smelted and cast into balls for Americans to pelt Englishmen with.”

The site on Crevecoeur’s map corresponds with a wetland northeast of Prospect Hill in Chilmark, nestled in a valley off North Road, draining into Roaring Brook. It was part of settler John Hillman’s homestead. (The Hillman home, built nearby circa 1725, was later made famous for its owner, actor James Cagney.) Iron was harvested from Hillman’s bog as early as 1743, when a deed first refers to his “iron ore swamp.” Rev. James Freeman, in his 1807 book ”Description of Dukes County” described, “There are several pleasant vallies between the hills; and some of them in Chilmark, about a mile and two miles from the Sound, afford iron ore, near runs of water and swamps. It sells for ten or eleven shillings a ton on the Sound; and considerable quantities of it have been exported to the forges on the Main.” The Hillman family reportedly had a dock on their northern shore, near Roaring Brook, where they shipped their sometimes-contraband iron ore.

In 1804, Dr. James Thacher of Plymouth also wrote of the “mine of iron ore of considerable extent and value” on the Vineyard. He wrote, “It is brought to our works in large lumps of a reddish brown colour, affording about 25 per cent and it is worth six dollars per ton. Iron from this ore exhibits a peculiar degree of smoothness and lustre.”

And it wasn’t just in Chilmark. Bog iron was also reportedly harvested commercially from the wetlands near the headwaters of Blackwater Brook in West Tisbury. Across the street from Lambert’s Cove cemetery lies the Look homestead, built about 1790 and now owned by the Athearn family. In the woods behind the house, according to Eleanor Mayhew’s 1956 book “Martha’s Vineyard, a Short History,” was another bog iron habitat.

A story has been widely repeated, attributed to both North Road and Lambert’s Cove bog iron. Charles Hine wrote in his 1908 history that during the War of 1812, Vineyard “bog ore” was shipped to a Colonel Murdock in Carver, “there to be smelted and cast into shot for the ‘Constitution’ when she was fitting out in Boston in 1814. Every pound of the ore was weighed on the Holmes Hole beach by Mr. Jonathan Luce, Sr., and then shipped in small ‘wood sloops’ to Wareham and thence taken to Carver. No sooner did the ‘Constitution’ receive these balls than she sailed, under command of Capt. Charles Stewart, for Madeira, where she attacked and captured the two British ships of war, the ‘Cyane’ and the ‘Levant.’ ‘It was Vineyard bog-ore that did the job.’”

Banks repeated the tale. “During the war of 1812,” he writes, the Vineyard “furnished the ore that was cast into balls for the guns of the ‘Constitution,’ if we may rely on legend, and it is not difficult to give this tale some credit.” Both Banks and Hines attributed the ore for the famous naval frigate (also known as “Old Ironsides”) to the North Road bog, but Mayhew sources it to Look’s bog on Lambert’s Cove. (It should be noted that several Islanders, including Chilmark bog-owner Robert Hillman and his North Road neighbor Col. George Claghorn, were closely associated with the construction of the U.S.S. Constitution.)

Looking for bog iron? Try exploring small bodies of standing water in peaty marshland near freshwater springs along our hilly northern moraines. Watch for still, tea-colored water, and iridescent oily films. Seek reddish, pea-sized deposits (sometimes as large as fist-sized) at the edges or feel for them at the bottom. Some foragers use a metal mining rod to probe the wet soil. Don’t trespass, and don’t hurt any Englishmen, but do share photos of your discoveries!


  1. I learned about bog-iron as a kid by dragging an old Model T Ford magneto magnet on a string through the sand on a beach near a boggy marsh. The little particles of iron collected on the magnet, and could be pulled off and saved. Good fun.

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