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Saltwater damage gold coins
Wahoo554
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From time to time I see gold coins slabbed details due to saltwater damage. It’s always interested me what the source of these coins might be, e.g. metal detectorists on the beach or shipwreck salvage. Does anybody have any input as to where some of these coins might come from or what causes the actual damage to the coin? I presume the damage is from friction between the coin and the sand, which suggests the coins may have come from an area with shallower water. Here’s a pic of an example currently up for auction on Heritage:
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Coins that aren't 24k gold - like classic U.S. coins - will show chemical damage in saltwater. It need not be friction.
Any idea why SSCA and coins from other prominent shipwrecks don’t suffer the same Ill effects? Could it be that the water has different chemical properties at greater depths, or that the coins were found in some sort of container that protected them?
Depth affects pressure, not much in the way of chemistry unless it is photo-initiated.
SSCA and other shipwreck coins do suffer the same affects.
Gold is not harmed by saltwater. But, when you see that on the slab think that this coins is resting in sand and sand is always subject to movement and that is what has happened. Sandwashed is a better term. Gold is not affected by saltwater in any way. Of course the 10% copper might be affected and that's the cause? I don't think so but perhaps.
bob
sand is abrasive, salt is corrosive (not sure if salt corrodes gold).
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I’m not aware of any SSCA gold coins that were details graded for saltwater damage. It seems the SSCA coins have a different tone at times which could perhaps be attributed to the saltwater environment, but none with the sand friction look. I’d be curious as to how many gold coins NGC has details graded for saltwater damage.
Hate to say it but my guess is the slabbed coins from major ship wreck finds may have been negotiated to not have net grades placed on them. Just the note of being from a ship wreck is enough to know they were submerged in salt water for many many years. It makes selling them easier without a detail grade. A TPG wants that kind of business. Good publicity, a very large submission. So a special label is agreed upon.
I know I would negotiate such a deal if I was in charge of selling that type of material.
my two cents.
I would think if it was damaged by the sand, it would say that, not saltwater. Who knows.
Cold slows chemical reaction times. Hot speeds them up.
Gold is less reactive than silver which is less reactive than copper.
So a 90% gold 10% copper alloy will have surface copper react...
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Regarding the SSCA coins, here's what @RogerB said in a previous thread:
"New coins were packed tightly in bags and boxes, then surrounded with sawdust. The packaging rotted with time, but the packed coins were largely protected from abrasive sand and fresh sea water contamination. Coins scattered during the wreck were more likely to have had surface wear or damage.
[PS: Sawdust absorbs considerable sea water and, under depth pressure, gradually becomes a natural sealant that protects materials packed in sawdust. Depending on the tree species it can also buffer certain chemical reactions.]"
link to previous thread
Just ran a quick SSCA search on eBay and this came up:
1857-S $20 Lib Gold SS Central America Shipwreck UNC Details PCGS - SKU#178803 https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.com/ulk/itm/143032997997
That’s the first environmental damage SSCA gold coin I’ve seen, though I’m sure there are more. Definitely a different look than many of the lustrous CAC approved MS ones that are also for sale on eBay.
https://ngccoin.com/specialty-services/shipwreck-coin-certification/effect-designation.aspx
Looks accurately graded to me.
Still itching with curiosity as to where the unattributed saltwater damage gold comes from. If from a known shipwreck one would want to maintain the provenance as it adds value.
Interesting discussion, thanks for sharing !!!
Sellers likely feel that this information would "tarnish" the reputation of other coins from the same source.
This shipwreck coin is NGC graded UNC DETAILS ENVIRONMENTAL DAMAGE:
Clive of India Treasure Brazil 6400 Reis 1750-R
Gold, 32 mm, 14.30 gm (approx), 0.4215 oz (0.917 fine)
These coins were on the ship "Doddington" which was wrecked off South Africa in 1755 and salvaged in 1977.
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Think of moving seawater as a slow motion sand blaster. Over time it removes the mint luster from otherwise Mint State coins. The details are there, but the luster is gone.
The high grade SS Central America coins were in the protected middle of the pile. The prices on the outside were effected by the seawater affects.
Unfortunately I saw a number seawater affected coins with straight grades at the current FUN show. If a coin is of the current sea salvage era (1850s) has a lot of detail, but no luster, you should approach such pieces with caution if they have straight grades.
Gold is totally unaffected by saltwater.... However, moving sand will affect the surface and the copper content (or silver content) can deteriorate in saltwater... thus affecting the surface of coins with those alloys. Cheers, RickO