Special surprise chunk of copper!

Beige · Jun 13, 2020

I was metal detecting an old school in the middle of a city in North Central Wisconsin when I got, what I thought could be a deep old silver signal. I started digging and with a little work I made it through some white pine roots and continued down about 12 inches. My pinpointer was almost touching the target so I reached my hand in and started brushing away some sandy soil expecting either an indianhead penny or a deep worn silver. I see some copper corrosion and think "bleh, just another chunk of melted copper." I pull the copper object out and to my surprise it is no ordinary chunk of copper. Turns out it is something with much more historic value. A moment I will never forget. I found a copper culture point dating anywhere from 3000-7000 years old.

I gently toothpicked dirt out of the attachment part of the point and then used distilled water and a soft brush to clean whatever I could. The brush didn't do much. Any advice on how to preserve it would be appreciated.

Seadog72 · Jun 13, 2020

Sweet find! Congrats! Did a little research, from a metal detecting site....

”Copper and brass relics need special attention. Detecting hobbyists frequently post their favorite cleaning methods in forums. Among them: for simple oxidation, a treatment can be made from a homemade mixture. It consists of two parts denatured alcohol, two parts distilled water and precipitate chalk—which makes a thick paste. This can be applied and removed from the object. For heavy copper corrosion, you can use a 5% solution of lemon juice. Let the item soak in the liquid for five minutes increments and gently rub the coating; this speeds up the cleaning process. After cleaning, neutralize the acidic juice by rinsing the item in a solution of water and 5% baking soda; then, rinse in clear water. Things to never use on copper and brass include: a liquid copper polish, or any compound containing chlorides or sulfur compounds.”

From: https://www.metaldetector.com/learn...c-hunting/cleaning-and-preservation-of-relics

A2coins · Jun 14, 2020

Banner thats a cool find thats a museum piece wowza

welsbury · Jun 14, 2020

Special find for sure. Maybe some more pics please.

Sidevalve45 · Jun 14, 2020

Congratulations from Black River Falls.

joshuaream · Jun 15, 2020

Really cool find, congrats!

On preserving copper relics, it really depends what you want to accomplish. But I would say if you keep it dry and in a relatively low humidity environment, you have sometime to decide. Maybe check with some local metal detectorists and see how they have preserved their finds. I have some old copper culture items that were found 50+ years ago, not preserved in anyway, and they are still solid items. (It does depend, some of them have a solid patina, but some of them do leave a bit of stain on your hands if you handle them, so eventually I'll need to get that addressed.)

From a collectable point of view, like coins, cleaning it can impact the value. But from a purely preservation point of view, active corrosion will eventually destroy it. (That might be in thousands of years if kept dry in a frame, or a couple of years if you hang it outside near the beach with a salty breeze.) I've seen a lot of copper relics in museums taken down to the shiny metal, and then coated to preserve that copper luster.

Personally, I wouldn't overclean it nor would I handle it excessively. Pure copper like that tends to get a stable patina and if kept in normal home room temperature/humidity conditions, it will likely be around longer than any of us will be.