What is Bog Iron? Long before high-grade iron ore was discovered in western Pennsylvania and carried in train cars to monstrous blast furnaces in Pittsburgh and Bethlehem to make structural girders, I-beams and rails – the NJ Pine Barrens churned out bog iron. Pots, frying pans, cookers and all manner of raw material for local “Smiths” to fashion into whatever implements colonists needed came from South Jersey – then known as “West” Jersey. Bog Iron was a Pine Barrens miracle.
You’ve heard of Batsto. How about “Batsto Furnace” or “Batsto Forge”? A couple of hundred years ago it was as precious to the American Colonies as Silicon Valley is to us today.
One thing the Pine Barrens has in abundance is Bogs. And groundwater. And trees. For those of us not schooled in geology, that’s all we see when we go on a hike down the Batona Trail in Wharton State Park or kyack down the Batsto or Mullica Rivers. It’s all about natural habitats and preserves, pigmy pines, sandy soil and tea-colored waterways. Peaceful. Serene. Very non-Jersey-like.
My wife and I regularly walk the beautiful grounds of Smithvile Park in Easthampton, Burlington County, NJ – again, very peaceful, serene and unique.
But there is something about South Jersey that is perplexing.
In North Jersey, streams run clear in most state parks. The Watchung Reservation, Jenny Jump, South Mountain Reservation, Hacklebarney, High Point……all have amazingly clear streams. The environmental movement has made great strides in keeping our state parks fairly well free of debris, old refuse and anything that is characterized as a “pollutant”. In Smithville Park, however, something jumped out at me (metaphorically speaking). An epiphany, of sorts.
I called over a Park Ranger that so happened to be nearby and ran my thoughts by him.
“Why”, I asked, “Are streams in North Jersey basically clear and here they run like somebody soaked a big teabag in them? And what’s the story with all that brown paint-like sludge that is everywhere the tea-stained water flows, oozing onto rocks and clumping into pools of glop?”
I couldn’t let go. “Is that brown glop pollution? I’ve seen it throughout the Pine Barrens, too! What’s goin’ on?”
The Park Ranger looked at me like I needed my head examined.
“The Pines account for some of the acidic tea color in the water” He patiently explained. “The brown glop you describe is a mixture of minerals and iron compounds that the acidic environment causes to leach up out of the soils……resulting in the iridescent oily film that is carried on the water. Good day.”
Yes, I felt foolish. I needed to do some research.
I guess didn’t realize that the very place where my wife and I were walking once was the palatial estate of Hezekiah Bradley Smith, who, in 1865, established an ironworks and forge in Easthampton. Why Easthampton? Because of the very “brown pools of glop” that I asked the Park Ranger about. They’re everywhere – and, properly harvested, they are the source of insoluble iron compounds that form just below the water surface into large rock deposits of what is called “Bog Iron Ore”.
Hezekiah Smith – the Patroon of Smithville Manor and Forge – was carrying on a South Jersey tradition that got its start in the Pine Barrens around the mid Sixteen Hundreds. The smelting of Bog Iron.
Most of the cannon balls George Washington used in the Mid-Atlantic Campaigns during the Revolutionary War came from Batsto Furnace (also called “Batsto Forge”). The Pine Barrens had the sand, oyster shells, wood, bog iron ore and smelters necessary to churn out pots, pans, hardware of all kinds, axles, anvils – and cannon balls. This was big industry at the time. Think low-tech Silicon Valley.
When Englishmen from Wales relocated to South Jersey (ie. “West Jersey” at the time), they quickly noticed geographical conditions were perfect for harvesting raw iron compounds that collected in the form of large brown rocks at the bottom of the Batsto and Mullica Rivers. An nascent iron industry was soon employing hundreds of people and shipping products throughout the Colonies by the 1660s
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Before Welshmen in England plyed the bog iron trade, Norse settlements in Newfoundland (Vinland) did – building on their iron working and smelting skills they brought from Scandinavia. The smelting and forging of bog iron dates back over one thousand years in Northern and Central Europe. Iron rivets found in Norse longboats and burial mounds in Britain were forged from bog iron as were their tools and swords. Pots and tools found in Poland and Russia from the same period were made from Bog Iron.
The iron-deposit rich rocks at the bottom of South Jersey acidic Pine Barrens rivers were worth their weight in gold. Enterprising souls could collect flat-bottom boats full of the ore (oftimes on other people’s property claims) and “Privateer” the precious commodity to the highest bidders. They were inland Pirates, coursing the streams and rivers of the Pine Barrens in search of “brown gold”. And in true Jersey fashion, none were too picky about which side – Revolutionary or Tory – paid them for their wares. Spanish silver “Pieces of Eight” was the preferred specie. British Pounds were preferable to Colonial Scrip or “Continentals”. Wherever there was coin to be made, Jersey Boys were first in line – and the Pineys showed everybody else how it was done.
What was this primitive technology that literally slaked the American Colonies iron appetite until the late Eighteen Hundreds? “Bog Furnaces”.
Bog Iron is smelted in a furnace. No – not a blast furnace. That appeared in the mid-Eighteen Hundreds and was mastered by Andrew Carnegie using high-grade Pennsyvania iron ore, coke and extremely high temperatures. Bog iron was a strictly low tech process thousands of years old. It didn’t require huge investments of capital and could be accomplished by crafty common people with an eye for details – and nature.
First of all, bog iron is “formed” when iron oxides – actually, “iron oxyhydroxides” (generally “goethite” (FeO(OH)) – encounter acidic ground water. The impure ferrite deposits in bogs or swamps oxidize into “ferric hydroxide” by action of iron bacteria acting as an enzyme catalyst. The end product is a hydrous iron oxide that accumulates in bogs or swamps. Streams carry this dissolved iron oxide in the form of a deep brown sludge – the brown “glop” one tends to see throughout the Pine Barrens and Smithville Park at the edges of tea-brown waterways.
This tan-paint-colored “glop” (or, as Pineys call it to this day – “iron slick”) is heavy with ferric hydroxides. Gradually, it sinks downward and forms brown, solid rock-like clumps of “bog ore”. These rich deposits are then collected – by anyone who has an eye to recognize them for what they really are – from the bottoms of streams and rivers and sold at a good profit to local smelters.
Now, I’m no chemist – but (apparently) the naturally occurring low PH and high acidic river water of Burlington and Atlantic County, NJ and generous amounts of iron bacteria here (Thiobacillus ferrooxidans and Thiobacillus thiooxidans – acting as “enzyme catalysts”) generate the “precipitation” of iron solids near groundwater discharges – such as creeks, meadows or bogs. The “iron slick” on the water surface is proof positive oxidation of iron minerals (ferrous oxides) is taking place. Bog iron ore-rich rocks are sure to be close by, just waiting to be snatched up
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The Pine Barrens was home to scores of Bog Ore harvesters (including “Privateers” who often poached other peoples’ “claims” on specific rivers or bogs) and smelters who did a land-office business providing the iron ingots to blacksmiths and armorers whose trade was to fashion products people needed to survive. The unique geography of the Pine Barrens made possible this entire industry – rivers, streams, sandy soil (the perfect conditions for oxydation of ferric hydroxide residues), wood (for charcoal fires), oyster and sea shells (for “flux”) and a rich chemical soup of natural, “geochemically active” microbes and plant detritus.
The raw bog iron ore was sold to a “Smelter”, the profession of the man who performed this function. He would then commence “smelting” – the process by which the elemental iron was isolated and drawn from the rock.
The smelting process took place in a “Bloomery Furnace”, a circular, clay-lined vertical shaft a couple feet in diameter and about a yard tall. The “clay” used was probably a mixture of sand, plant fibers and horse dung. The structure was strong enough to hold the bog ore-rich deposits inside of it and radiate heat inward – and sturdy enough to prevent its walls from melting and mixing into the ore slag.
Furnace building was a learned skill, as was the smelting process itself, handed down from father to son. The furnace was positioned atop a series of staggered bricks, arranged to be open at center, into which wood was positioned to propel a heat draft upward into the clay-lined shaft furnace chamber. Oyster and clam shells were used (in quantity) for “flux”, an additive to promote melting of the iron molecules into concentrations of iron product inside the “slag”.
Pilot openings were positioned in the burner foundation to enable air flow to be increased or shut off so that a relatively constant fire temperature could be maintained. Bellows, of course, drove these flames to desired temperatures of 1100 to 1300 degrees Fahrenheit. A “run” of molten iron down the inside of the “Bloomery Furnace” flowed down into oblong troughs or “Pigs” – cavities dug into the furnace base to capture concentrations of iron product.
This “Pig Iron” would have already picked up carbon by having made contact with layer upon layer of charcoal inside the furnace chamber. “Pig Iron” was full of impurities – but it was the holy grail of ingots for iron production at the time.
Pine Barrens smelters burned charcoal that was indigenous to South Jersey. The charcoal industry in New Jersey developed contemporaneously with bog iron smelting and glass making in a kind of industrial symbiosis. Settlements in New Jersey and the mansions of Philadelphia had need of Jersey glass, charcoal and iron implements.
In archeological digs at early Viking settlements in Iceland (Skogar, Reykholt, Stong and Vatnsfjorour) and Sweden (Mastermyr), bog iron smelting furnaces were found to burn peat as well as charcoal. Bellows were critical to drive smelting kiln temperatures high enough to generate iron slag.
Their furnaces were called “Bloomery” furnaces because the end result of the burn was a “bloom” – or congealed mass – of red. glowing low-carbon iron, slag and charcoal. It resembled a big, extremely hot flower. As the “bloom” cooled, slag and charcoal residues were knocked off. What remained was a lump of iron, ready to be hammered and forged into a weapon or implement.
The earliest bog iron ore producing site in North America was in St. John’s, Newfoundland, being worked by an Englishman named Anthony Parkhurst in 1578. Early efforts to mine bog iron ore in the American Colonies occurred around 1619 in Chesterfield County, Virginia (Falling Creek Ironworks). The Saugus Ironworks in Saugus, Massachusetts commenced bog iron ore foundry operations in 1646.
Bloomery furnaces were exclusively utilized in New Jersey, constructed with elaborate and distictive base trough designs, ie. the “Pigs” to draw off the final product – molten iron ore. While Tinton Falls in Monmouth County claims bragging rights for having the first “commercial bellows iron furnace” (1684), the Pine Barrens had a fully-functioning cottage “Bog Iron” industry turning out bog iron ingots in quantity by 1675. Generations of Pineys were by that time engaged in the trade and Mt. Holly was known as an iron business hub.
By the time of the American Revolution, Pine Barrens foundries were even mixing their locally-sourced bog iron ore with higher quality ores from as far as England to produce a stronger, more adaptable product. Slowly but surely, the science of metallurgy was evolving and smelters were experimenting with their processes to discover ways to produce greater quantities of high-quality bog iron product and “pig” ingots that could be traded for goods, services and international specie.
By 1776, the Pine Barrens – specifically Batsto Foundry – was a key geographic and strategic location given its status as an iron cannon ball supplier and weapons-grade iron producer.
Bog Iron, charcoal and glass were big industries in the Pine Barrens.
Today, hike the Batona Trail, wander through the Harrisville “ghost town” and take in the Great Papermill Ruins. You’ll see crumbled foundations and and ruined structures everywhere. Places where people like you and I hundreds of years ago scraped out a living making iron the old-fashioned way and hustling the charcoal and glass trades.
Copyright, Jon Croft, 2021.
*My thanks to Wikipedia; Hurstwic “Iron Production in the Viking Age” www.hurstwic.org; www.njpinebarrens.com – Towers of Fire: Iron Production in the New Jersey Pine Barrens; www.revolutionarywarjournal.com; The Journal of the Society for Industrial Archeology, www.jstor.org; www.nationalmaterial.com – A Brief History of the American Steel Industry; www.fs.usda.gov – The Beginning of the Iron Industry in America; https://pubs.er.usgs.gov – The North American Iron Ore Industry;
