Horn Silver

Discussion in 'Ancient Coins' started by physics-fan3.14, Sep 4, 2016.

  1. physics-fan3.14

    physics-fan3.14 You got any more of them.... prooflikes? Supporter

    So, I've been lurking here on the ancient forums, and I've been reading a couple of books to get acquainted with ancient coins.

    One term that I keep seeing, but I'm unfamiliar with (the term isn't used for "modern" coins) is "horn silver."

    Could you guys please explain:

    1. Exactly what it is?
    2. What causes it?
    3. What effect it has on coins, especially the surface underneath?
    4. How it affects grade and value?
    5. Any conservation methods which are effective?

    And, if you have pictures to show what it is, that would be helpful.

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  3. TIF

    TIF Always learning. Supporter

    Horn silver is silver chloride (AgCl). On ancient silver coins, it is sometimes seen as a dull gray or black tenacious deposit. I'm unaware of any easy way to remove it without harming the underlying surface, although I have seen sodium thiosulfate recommended as a removal agent (soak the coin in a solution of sodium thiosulfate).

    This Ptolemy I tetradrachm has what I believe is a scattering of horn silver (the rough stuff on the surface). On this coin it's not terribly distracting and the coin was not inexpensive so I'm not going to try to remove it.


    EGYPT. Ptolemy I Soter
    AR tetradrachm, 27 mm, 17.0 gm (Attic standard)
    Alexandreia mint, struck 313/12 BCE
    Obv: Head of the deified Alexander III to right, wearing mitra of Dionysos and elephant skin headdress, with aegis around his neck, and with horn of Ammon on his forehead
    Rev: ΑΛΕΞΑΝΔΡΟΥ; Athena Alkidemos advancing right, hurling spear with her right hand and with shield over her extended left arm; to right, eagle with closed wings standing on thunderbolt to right with ΔΙ below
    Ref: Svoronos 33; Zervos series D, issue XIII; SNG Copenhagen 14; BMC 7
    Last edited by a moderator: Mar 12, 2021
  4. desertgem

    desertgem MODERATOR Senior Errer Collecktor Moderator

  5. red_spork

    red_spork Triumvir monetalis

    Another option if it comes down to it is to have it professionally cleaned. People who clean coins are a dime a dozen but there are a handful of people out there who do it for a living and work with the major dealers and auction houses to clean hoards and things like that. It isn't cheap but it's something to consider if you ever decide that it is distracting.
    rrdenarius likes this.
  6. physics-fan3.14

    physics-fan3.14 You got any more of them.... prooflikes? Supporter

    Do you know if this is something that NCS does? I have sent coins to them in the past and been well pleased with their work, but I don't know if they do ancients.
  7. physics-fan3.14

    physics-fan3.14 You got any more of them.... prooflikes? Supporter

    Good info, TIF, thanks.
    TIF likes this.
  8. desertgem

    desertgem MODERATOR Senior Errer Collecktor Moderator

    The consideration for cleaning would be that it is extremely soft ( 2-3 Moh Hardness) and it is not water soluble, and also I would imagine, one would have to protect the newly exposed surface. Originally the metal was oxidized and "desert winds" polished it to the current color. If it brominated, ( areas contain Bromine in soil), it will react different from strictly being silver chloride.If not AgCl will blacken rather quickly when freshly exposed to bright light. I assume original location would be important to know for local bromine availability. Interesting question! Jim
  9. physics-fan3.14

    physics-fan3.14 You got any more of them.... prooflikes? Supporter

    Thanks, desertgem.

    How does the presence of horn silver affect the grade, eye appeal, and value of coins?

    Any other pictures people have will be appreciated, so I can understand what I'm looking for.
  10. Jwt708

    Jwt708 Well-Known Member

    I know you haven't asked but I'm going to say it - a great way to to get acquainted is buying a couple! You can get some nice bronze or silver coins for very modest prices like around $20.
  11. David@PCC

    David@PCC allcoinage.com

    Imagine a hoard of silver coins in a large ball underground. As time passes the outer coins begin to degrade from exposure to the elements and soil, gravity deposits the broken down silver from those coins onto others below it. After a long time of this, a build up occurs on the silver coins beneath and adheres to it almost like cement. Here is my example
    Some of it comes off relatively easy
    But the deposits directly touching the host coin are much harder similar to TIF's.
    stevex6 and TIF like this.
  12. TIF

    TIF Always learning. Supporter

    On Vcoins I ran a search for "horn silver"; here are the results. I didn't look at each hit and can't say whether the sellers' reporting of horn silver is accurate. Perhaps it will be a good avenue for seeing its varying appearance on coins.

    The same search in CNG's archives yielded 2670 hits. Note that the results are in tabs: Coin Shop / eAuctions / Printed Auctions. When you click the link you'll be on the Coin Shop tab.

    Edited prior to posting: For some reason when I ran the search and clicked over to the other tabs, the search parameters were lost and a gazillion hits were returned. Therefore, I'm posting the search results separated by the avenue of sale:

    CNG Coin Shop
    CNG eAuctions
    CNG Printed Auctions

    Determining how its presence affects price will be very difficult since the overall quality/appeal/price of any given ancient coin is much more complicated than with moderns. You could pick a few of the horn silver hit result coins and then search CNG's archives for similar coins (with similar strike, style, and preservation) and see what you think. You'll also need to consider date of sale in that equation. Not an easy task!

    Note: some of the hits do not have horn silver. Despite the use of quotes, the search results appear to have returned results when searching the words separately. You'll have to click on a coin and read the description to see whether the coin was said to have "horn silver".

    That said, I don't think it is terribly important. Just assess the given coin for what it is. The presence of some horn silver may not be particularly detractive for some coins.

    Edited again: a large number of those CNG hits do not have horn silver, sorry! :oops::D
    Last edited: Sep 4, 2016
  13. physics-fan3.14

    physics-fan3.14 You got any more of them.... prooflikes? Supporter

    Yes, I have bought a couple inexpensive ancients just to get my feet wet. I'm in "learn as much as I can" mode right now, since ancients are a bit different. Once I figure out what I like, and feel like I understand enough to not make any expensive mistakes, I'll start buying more.
    Jwt708 likes this.
  14. physics-fan3.14

    physics-fan3.14 You got any more of them.... prooflikes? Supporter

    Very useful, thanks!

    So, horn silver is basically a type of corrosion. Would you say that it is a strong negative, like verdigris, or just a general negative? Which is worse for grade/value/eye appeal - horn silver, or porosity? (both of which are from corrosive processes, and/or environmental damage)

    Obviously, all things being equal a coin without horn silver is going to be more desirable, but I'm just trying to figure out how bad this stuff is. On an American coin, this would make it almost unsaleable - but the ancient collectors tend to treat things a bit differently.
  15. Jwt708

    Jwt708 Well-Known Member

    And you haven't shared them!:jawdrop:
  16. physics-fan3.14

    physics-fan3.14 You got any more of them.... prooflikes? Supporter

  17. TIF

    TIF Always learning. Supporter

    I don't think that's an answerable question because of the great variations among the same coin types due to each being hand-struck using many different dies. In general though, if the horn silver isn't thick and if it isn't covering devices, it probably won't lower the value much.

    Using the Ptolemy tet I posted as an example, I do think the presence of horn silver played a small role in its comparatively low price, but so did the wear. The precise type (Svoronos 33, the earlier style of elephant headdress tet/Athena reverse; before the weight standard was lowered) is arguably of finer style than the subsequent issues. I wanted this earlier style but wasn't willing or able to purchase one without such wear and horn silver. That, plus they aren't as readily available as the later types.

    If faced with choosing between the coin I bought or a later style version without a light coating of horn silver in the fields-- even if the it had less wear-- I'd still choose this coin even if they were priced the same. That's a personal decision though; you might prefer the later style :)
    rrdenarius and Jwt708 like this.
  18. Jwt708

    Jwt708 Well-Known Member

    Here's the challenge, there is no good answer. I would buy Sallent's coin and think it's fine. For me value is challenging to pin down because there are so many things worth considering.


    I even commented there! Haha!
    TIF likes this.
  19. desertgem

    desertgem MODERATOR Senior Errer Collecktor Moderator

    I would consider it "like corrosion in toning of modern US coins", some desire it, others dismiss it.
  20. physics-fan3.14

    physics-fan3.14 You got any more of them.... prooflikes? Supporter

    So some actually consider horn silver a positive? Huh. Interesting.

    New question: I realize that for many, third party graders and ancient coins are considered a curse word. However, coming from US collecting, it is the standard. How does NGC treat horn silver? Do they denote it on the slab, or do they take points off in the "surfaces" score?
  21. TIF

    TIF Always learning. Supporter

    I can't imagine that to ever be the case, but can believe it possible for horn silver to not be a significant negative (as described in my prior post).

    Good question, and most of us probably won't know because we don't pay attention to what the slab says :D.

    I'd guess they lower the surfaces score. It's a good question though. Maybe I'll cruise Heritage's archives and see if any slabs say "horn silver". My bet is that they just ding the surface grade, although with the great variability in how they grade it may not be possible to determine how the surface grade would be affected.
    red_spork likes this.
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