Written by the Treasureguide for the exclusive use of the Treasure Beaches Report.
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| Recent Metal Detector Finds by Mark D. at Jensen Beach. |
Mark D. submitted the following email and the find photos regarding a recent hunt at Jensen Beach.
I have been watching Jensen Beach all week and you can’t really see it through the cameras but the sand is shifting. High tides brought on buy the full moon and a little wind and storms to kick up the surf and the summer build up is moved around. I found cuts at some Hutchinson Island beaches but Jensen Beach was the most interesting. I went out today Monday after work at dead low tide. At dead low tide you could see it, the steep slope you don’t usually see at JB. But realistically it’s just the fresh sand that came in going back out again. But low in the slope I hit 3 good targets right at the hard, hard shell layer where I actually needed the water in the hole to dig deeper. I only had those 3 finds until I was pushed up the slope by the tide then went to dry sand. Long story short, I found a Swiss coin dated 1964 and a NYC transit token that hasn’t been produced or used since 1970 (small Y cutout). The 3rd find was a 2022 dime I found further up the slope. Here’s my question why do they look like they just came out of circulation?
I asked my copilot a lot of questions about what I found, the token is solid brass the coin is Copper-nickel (non-magnetic). But I have got to say I have seen brass copper and nickel not that old completely eroded. Another theory is that it was buried in an oxygen deprived deep layer?
Anyway I haven’t seen anything like this before maybe I’ll see it again just puzzles me the condition these finds are in, no cleaning, nothing just as I dug them up hours ago.
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Thanks for your observations, photos and question Mark. Way to dig out those hard to get targets.
Finds can be surprising. After centuries some are in great condition while new items come up barely recognizable. I always say you can't tell how long an item has been on a beach by its age. A centuries old item can be dropped at a very recent date. I feel confident that some old items I've found were very recently dropped. You'll see people wearing old stuff on the beach. You'll see guys wearing 1715 Fleet coins for example. I found one old shipwreck coin that my research suggests was lost and found possibly three times. But putting all that aside for now, let's assume that your finds were lost years ago, which is a real possibility.
Before going any farther, let me warn you that I don't have a very good answer, but I will give you some thoughts to consider.
There are multiple factors to consider and not knowing the precise circumstances of where the items have been hiding or for how long, the results can be surprising and hard to explain.
As we all know, some metals corrode more quickly and easily than others. Gold coins usually stay very nice even after centuries of salt water immersion. Zinc pennies, on the other hand, fall apart very quickly despite not facing severe circumstances and despite the fact that zinc is considered by engineers to be fairly corrosion resistant. The problem being that they are not pure zinc but layered. See the explanation below for more detail on the zinc penny problem.
So one important factor is the metallic composition. Some types of coins simply do better than others, and brass and nickel, while they can corrode are among some of the better ones - certainly better than zinc and silver. Still you will find a huge range in the condition of dug silver and other coins.
So besides the metallic composition, environment of the items will have an effect. As Mark points out, coins can be protected by the immediate environment. What makes that so complex is that the environment can change many times in the surf or on the beach front.
Besides other things other nearby metals can have a protective or destructive effect on the item.
In my opinion, and without knowing how long they have actually been out there, they items are not among the most easily corroded metals. Most of the cuprous beach or surf tokens I've found have been in pretty good condition, although a few were badly corroded. Bronze spikes come up beautifully compared to iron, which are typically badly rusted if not reduced to a void. They do however have a relatively nice patina.
I'm thinking that Marks finds are not the worst metals for corrosion, were probably not in the worst possible environment, and here comes the new part - The items could have been tumbled clean by the surf and shell media.
So I can't answer the question, but there are my thoughts. Below is Copilot's explanation of why zinc pennies corrode so badly.
Why Zinc Pennies Corrode Easily
1. Thin Copper Plating
Post-1982 U.S. pennies are 97.5% zinc with a thin copper plating (~2.5%).
If the copper layer is scratched, worn, or compromised, the underlying zinc is exposed—and that’s where trouble starts.
2. Galvanic Corrosion
When two dissimilar metals (like copper and zinc) are in contact and exposed to moisture or electrolytes (like salt from your fingers or the environment), galvanic corrosion occurs.
Zinc is more reactive than copper, so it acts as the sacrificial anode—it corrodes to protect the copper.
Once the copper plating is breached, the zinc corrodes rapidly, often forming white powdery deposits (zinc oxide or zinc carbonate).
3. Environmental Exposure
Zinc is vulnerable to acidic environments, like those created by pollution, acidic rain, or even skin oils.
Pennies left in soil, water, or humid conditions corrode faster due to the electrochemical reactions between zinc and environmental acids.
4. Poor Alloy Design for Longevity
The zinc-core penny was designed to be cheap, not durable.
Unlike galvanized steel (where zinc is intentionally used to protect the steel), the penny’s design unintentionally sets up a corrosion-prone system once the copper layer is compromised.
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Here is some interesting Jensen history from a blog post on Langford Landing and Frances Langford. (I don't see the date of the original article.)
Over time, inspired by her travels, Frances and her husbands created a tropical paradise known far and wide. Cottages, a restaurant, a marina, palm trees, rare foliage, freshwater ponds, peacocks, and even swans graced the property. Famous movie stars often visited. She gave Martin County a reputation and she put it on the map. She made Martin County’s Jensen Beach her permanent home.
Frances chose to build her personal residence near Mount Pisgah, the highest point of the peninsula. Lore has it that pirates and Indians once lived here too, standing on the high bluff looking for passing ships in the ocean. The property is steeped in beauty, history, and mystery. Sadly, in the end, the remaining 53 acre parcel was treated like any other piece of real estate.
After a long wait since the 2008 Great Recession, the property is finally being developed ironically as “Langford Landing.” The manner in which this is being done has taken most us by surprise...
And here is link to an old post I once did on pirate Don Pedro Gilbert and the history of the treasure lore of Jensen and Sewall's Point.
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| Source: nhc.noaa.gov. |
So Erin is on the same track. Supposed to stay to the east of us but is expected to be sending us some long-awaited higher surf.
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| Source: SurfGuru.com. |
SurfGuru is predicting up to a six foot surf, which is something we haven't seen for quite a while.
Good hunting,
Treasureguide@comcast.net