Share my fun: describing and cleaning a small roman hoard

Discussion in 'Ancient Coins' started by Roerbakmix, Oct 18, 2020.

  1. Roerbakmix

    Roerbakmix Well-Known Member

    Please join me in this fun project. This small Roman hoard of 15 AR antoniani was found recently, and I have been asked to describe and clean it.

    In this first post, I will show the 15 coins, and in later stages show the uncleaned / cleaned comparison photo's in combination with a description. I regard this as a fun project, but probably you'd so as well. So, please join the fun. Feel free to provide a description of one or more coins!

    Reverse: upload_2020-10-18_10-55-42.png
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  3. Orange Julius

    Orange Julius Well-Known Member

    Looks like a fun group of coins (mostly Postumus) that should clean up well! Philip, Philip II, Valerian, Gallienus, Salonina, Postumus... can't tell what #3 is.

    Good luck, I'll be looking forward to seeing your progress!
    thejewk, Inspector43 and +VGO.DVCKS like this.
  4. Roman Collector

    Roman Collector Supporter! Supporter

    What a fun project, @Roerbakmix!

    Number 2 and 7 are the same -- a VENVS FELIX issue of Salonina issued during Gallienus' joint reign with Valerian. Here's the one from my collection:

    Cornelia Salonina, AD 253-268.
    Roman AR Antoninianus, 4.10 g, 21.3 mm, 12 h.
    Cologne, AD 257-259.
    Obv: SALONINA AVG, diademed and draped bust, right.
    Rev: VENVS FELIX, Venus seated left, extending hand to child at feet; transverse scepter in left hand.
    Refs: RIC 7; Cohen 115; Hunter 24; RCV 10655.
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    +VGO.DVCKS Well-Known Member

    Solidly great material. Looking forward to news of your progress.
    Inspector43 likes this.
  6. Finn235

    Finn235 Well-Known Member

    Is this an actual hoard dug out of the ground together? If so, very interesting to see a Philip II in the mix - I guess akin to finding a silver quarter in your change today.
    Pellinore, Inspector43 and +VGO.DVCKS like this.
  7. ominus1

    ominus1 Well-Known Member

    ..kool lil group o 7 looks very interesting to me.:)
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  8. Sulla80

    Sulla80 one coin at a time Supporter

    This looks like a nice find - where did they come from? They all look nice to me, I hope they don't get cleaned too much ;)

    #7 - Salonina with Venus Felix?

    and an attribution for #8 which I see as : Gallienus, AD 253-268. AR Antoninianus, Colonia Agrippinensis (Cologne) mint. 1st emission, AD 257-258.
    Obv: GALLIENVS P F AVG, radiate cuirassed bust right
    Rev: GERMANICVS MAX V, Two captives seated at the foot of a trophy, their arms tied behind their backs.
    Ref: RIC V Gallienus (joint reign) 17, Göbl 872d
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  9. Roerbakmix

    Roerbakmix Well-Known Member

    Here is a photo of a photo... will post the results of nr 1 and 2 this evening.
    62CD8F6C-79AE-4800-A510-4BDF7E6AE7E1.jpeg F1BE1BF2-98DF-401E-87D9-39E0AB17ED16.jpeg
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  10. Inspector43

    Inspector43 72 Year Collector

    That is my kind of fun. I am sort of a collector. But, I am only interested in the cleaning, identification and attributing. I have finished my goal of cleaning and identifying 100 coins.
    Pellinore and +VGO.DVCKS like this.
  11. ancient coin hunter

    ancient coin hunter I dig ancient coins...

    Nice group of coins and many should clean up well. You should be happy with the lot.
    +VGO.DVCKS and Inspector43 like this.
  12. Roerbakmix

    Roerbakmix Well-Known Member

    Exactly the type of response I hoped for.

    I asked the owner this. He found the 15 coins in the same context, closely together (southern part of the Netherlands), but not in the same deposit. It's probably a dispersed hoard.

    A relatable coin. I mainly clean silver coins, and this is a fun project. Coins with a high silver purity are often relatively easy to clean. These antoniani are more difficult given that a) the silver content is low, b) the deposits are though and c) there is a nice patina, so there's something to loose.

    This project is interesting for me as it gives me the possibility to try different cleaning techniques.

    That having said, here are the first two. I used hydrogen peroxide (h2o2) 35%. Use this with caution, as it will cause instant burns.
    I think this one turned out rather nice. There are still some iron oxide deposits on the reverse, and a thin layer of horn silver on the obverse, but in hand, these deposits are almost unvisible.

    This one turned out to be a bit more pitted. I was afraid this would happen (see for example the roughness of the legend at the obverse between 9-1 o'clock), however, the H2O2 wasn't very gentle with the coin either.
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  13. Roerbakmix

    Roerbakmix Well-Known Member

    Nr. 3:
    A combination of copper encrustations, and horn silver. Treated by short immersion (60 seconds) in hot (100c) inorganic citric acid solution, followed by a very brief (30 sec) immersion in natrium thiosulphate.

    Nr. 4: Some copper deposits and a thin irregular layer of horn silver, covering mainly the obverse. Treated the same way as nr. 3, but only very brief citric acid (30 sec) and longer period in natrium thiosulphate (120 sec).
    Last edited: Oct 18, 2020
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  14. Inspector43

    Inspector43 72 Year Collector

    The first one below is a fully silvered campgate. It is a silver wash that was very difficult and slow to clean and save the thin silver finish. The next is a Probus Campgate SMTSB Combine.jpg Probus with silver obv.jpg Probus with silver rev.jpg that was silver plated. Both were just a chunk of dirt when I started. I have several others that turned out to have silver on them.
  15. dltsrq

    dltsrq Grumpy Old Man

    Congratulations to the finder! I was surprised to find that metal detecting has only recently been legalized in the Netherlands, where a portable antiquities scheme modeled on that of the UK has also been set in place. I do hope the find will be reported and thereby incorporated into the official archaeological record. It is good to see the Netherlands taking an enlightened approach to collecting!
  16. Sulla80

    Sulla80 one coin at a time Supporter

    @Roerbakmix, interesting to see your before and after - I am curious to see the mints and years of all coins once you are done:
    RIC V Salonina 7 Lyon, France (Lugdunum, Gallia) mint, AD 257-258
    RIC V Postumus 86 Lugdunum, Gallia mint, AD 260-269?
    RIC V Postumus 326 Cologne, Germany mint, AD 260-269?
    RIC V Postumus 315 Cologne, Germany mint, AD 260-269?

    I don't know coins of Postumus well enough to distinguish "more curlier hair above brow, more detailed beard, and more pronounced smile" - all of which would suggest Lugdunum over Cologne.
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  17. Roerbakmix

    Roerbakmix Well-Known Member

    Thanks so far for the ID's!

    imgonline-com-ua-twotoone-1QJXZ6Z7MYYi.jpg A thick layer of rock-hard dirt, and entirely covered in an encrustation of copper. Treated with 1) citric acid (about 3 minutes), followed by 2) local application of oxalic acid (note: poisonous), finished by 3) sodium thiosulphate.
    Very heavy with 4.45g

    Nr. 6
    Not entirely happy how this one turned out. Treated much the same way as nr. 5, the coin became a bit more pitted than it was. Probably due to oxalic acid.
  18. Roerbakmix

    Roerbakmix Well-Known Member

    Nr 7:
    This one was obviously difficult. The encrustation on the obverse was more than 1mm in thickness, and below the copper deposition was a thick layer of iron oxide which is very difficult to treat. In the end, all encrustations were gone, but at the cost of some minor pitting, mainly on the obverse.
    Accidentally, the oxalic acid solution became too hot, and the coin became very dark-red, which was removed by gentle rubbing.

    Nr. 8:
    Fairly easy to clean.

    Nr. 9:
    The main problem with this coin was the thick deposition on the obverse, at te radiate crown. Overall, the coin was somewhat rough.

    Nr. 10:
    Not really happy how this one turned out, but I had to be careful, as the coin seemed very fragile.
  19. Orielensis

    Orielensis Well-Known Member

    I see Philipp II (1x), Valerian I (1x), early Gallienus (2x), early Salonina (2x) and Postumus (9x). Thus, if you want to establish a terminus post quem for the burial of this hoard, you wil have to date the Postumus antoniniani. The best resource for this would probably Jerome Mairat's dissertation (online here). I don't know of a more recent or more detailed work on the chronology of the coinage of the Gallic Empire.

    No. 14 is a the relatively scarce and popular Serapis reverse of Postumus. No. 15 ist a Jupiter type not seen that often either. Maybe you want to take extra care with the cleaning...

    I recognize a few of the types from my own collection:

    #4 and 11
    Rom – Postumus, Antoninian, Moneta.png
    Postumus, Gallic Roman Empire, AR antoninian, 262–266 AD, Trier mint. Obv: IMP C POSTVMVS P F AVG; bust of Postumus, radiate, draped, cuirassed, r. Rev: MONETA AVG; Moneta, draped, standing l., holding scales in r. hand and cornucopiae in l. hand. 23mm, 2.96g. Ref: Mairat 246–7/320–1; RIC V Postumus 75/315.

    # 5 and 10
    Rom – Postumus, Antoninian, Kaiser stehend.png
    Postumus, Gallic Roman Empire, AR antoninianus, 261 AD, Trier mint. Obv: IMP C POSTVMVS P F AVG; bust of Postumus, laureate, draped, cuirassed, r. Rev: P M TR P COS II P P; emperor helmeted, standing l., holding globe in r. hand and long spear (points up) in l. hand. 24.5mm, 2.94g. Ref: Mairat 108/109; RIC V Postumus 54.

    Rom – Valerian I, Antoninian, Oriens.png
    Valerian I, Roman Empire, AR antoninianus, 258–259 AD, Cologne mint (RIC: Lugdunum mint), Obv: VALERIANVS P F AVG; draped, cuirassed, radiate bust of Valerian I r. Rev: ORIENS AVGG; Sol standing l., raising r. hand and holding globe in l. hand. 21mm, 2.86g. Ref: RIC V Valerian 13.

    Rom – Gallienus, Antoninian, Köln, Germanicus.png
    Gallienus, Roman Empire, AE antoninianus, 258–259 AD, Cologne mint. Obv: GALLIENVS P F AVG; bust of Gallienus, radiate, cuirassed, r. Rev: GERMANICVS MAX V; trophy between two captives. 20.5mm, 3.58g. Ref: RIC V Gallienus (joint reign) 18.

    Rom – Philip II, antoninian, Principi Iuvent.png
    Philip II, Roman Empire, antoninian, 245–246 AD, Rome mint. Obv: M IVL PHILIPPVS CAES; bust of Philip II, radiate and draped, r. Rev: PRINCIPI IVVENT; Philip II standing r., holding spear and globe. 23mm, 4.01g. Ref: RIC IV Philip I 216c.
  20. dopey

    dopey New Member

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  21. Roerbakmix

    Roerbakmix Well-Known Member

    Thanks @Orielensis for the ID's and the resources.

    Not a chemist, but a MD. I do know a thing or two about chemistry, but my knowledge is limited and mainly learn by doing. This small hoard is interesting as the composition of these 15 coins is similar and the depositions are similar, giving me the possibility to try different techniques and monitor the results.

    I'm happy with the results of most, but nr. 2, 6 and 9 not so much (though in hand, the minor pitting is less visible than on these macro photo's).

    I'll try to do the remaining 5 tomorrow.
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