Hack Silver Authenticity?

atom

I doubt there's any TPG that certifies hack silber, the medium of exchange prior to coinage, using the weight of the silver in commerce.
Does anyone know how to verify a claim that the silver fragment is actually as old as claimed, and the source/origin geographically.

Sapyx

For anything pre-coinage, there will always be debate about whether or not specific types of precious metal object should be counted as proto-money, and therefore of interest to numismatists. Celtic silver and gold "ring money", for example - they're often listed as proto-coins, and sold as such by the dealers who are trying to sell them, but there is rarely any surviving archaeological context for such objects. They presumably had dual "function" - primarily as jewellery/decorative items, secondarily as valuable objects for use in bartering.

As for the OP's main question - is there any way of independently verifying the age and/or geographical origin of a silver piece? I have a book, "Metallurgy in Numismatics", which is a collection of academic research papers that look into the feasibility of this question in various coin series. In short, if a coin (or other silver object) can be reasonably assumed to come from freshly-mined silver, then studying the trace impurity levels and comparing this to known impurity levels from various ancient mining sites, can give an indication of the likely place of origin of a piece of silver. However, if the silver is of mixed origin, or is recycled, with components coming from various sources and ages, or if the silver comes from some source unknown to archaeologists, then there is no way to tell the origin by chemical means. But they have used this method to determine, for example, that most of the hoards of hacksilver found in Israel are of Spanish or Sardinian origin, the silver having been brought to Israel in ancient times by Phoenician traders.

As for age, this is perhaps more reliable. Ancient metallurgical techniques were not as good at filtering out certain impurities from gold and silver, and modern metal refining can sometimes add impurities that would have been unknowable to the ancients (such as titanium). Trace chemical analysis (measured non-destructively by x-ray fluorescence) can thus say with reasonable confidence, whether or not a piece of silver was refined in ancient or modern times. Of course, if a counterfeiter melts down some genuine (but worn) old silver coins to make the raw silver for their fakes, chemical analysis could not spot the difference. You need something more.

Silver, like many other metals, becomes more brittle over the centuries, due to a process known as "recrystallization". A mediaeval silver coin that would have simply bent when it was freshly minted hundreds of years ago, would snap clean in half if you tried to bend it today. This recrystallization can be observed non-destructively, using x-ray diffraction to study the crystal structure of the metal; using this technique, it is possible to tell whether a piece of silver was melted and forged in centuries past, or more recently.

However, if you, a private collector, wish to get these tests done on a piece of hacksilver you own, it might prove difficult. Archaeologists don't like collectors, and the machines and databases needed to do these analysis might not be made available for collector use. I know the archaeology department in the university where I work does not let anybody but archaeologists use their XRF/XRD machine.

amwldcoin

@Sapyx They determined where the lead cross found on Oak Island was from using this method! (well the source of the lead anyway)

atom

@Sapyx Thank you for your detailed post!!

Oldhoopster

@Sapyx said:
For anything pre-coinage, there will always be debate about whether or not specific types of precious metal object should be counted as proto-money, and therefore of interest to numismatists. Celtic silver and gold "ring money", for example - they're often listed as proto-coins, and sold as such by the dealers who are trying to sell them, but there is rarely any surviving archaeological context for such objects. They presumably had dual "function" - primarily as jewellery/decorative items, secondarily as valuable objects for use in bartering.

As for the OP's main question - is there any way of independently verifying the age and/or geographical origin of a silver piece? I have a book, "Metallurgy in Numismatics", which is a collection of academic research papers that look into the feasibility of this question in various coin series. In short, if a coin (or other silver object) can be reasonably assumed to come from freshly-mined silver, then studying the trace impurity levels and comparing this to known impurity levels from various ancient mining sites, can give an indication of the likely place of origin of a piece of silver. However, if the silver is of mixed origin, or is recycled, with components coming from various sources and ages, or if the silver comes from some source unknown to archaeologists, then there is no way to tell the origin by chemical means. But they have used this method to determine, for example, that most of the hoards of hacksilver found in Israel are of Spanish or Sardinian origin, the silver having been brought to Israel in ancient times by Phoenician traders.

As for age, this is perhaps more reliable. Ancient metallurgical techniques were not as good at filtering out certain impurities from gold and silver, and modern metal refining can sometimes add impurities that would have been unknowable to the ancients (such as titanium). Trace chemical analysis (measured non-destructively by x-ray fluorescence) can thus say with reasonable confidence, whether or not a piece of silver was refined in ancient or modern times. Of course, if a counterfeiter melts down some genuine (but worn) old silver coins to make the raw silver for their fakes, chemical analysis could not spot the difference. You need something more.

Silver, like many other metals, becomes more brittle over the centuries, due to a process known as "recrystallization". A mediaeval silver coin that would have simply bent when it was freshly minted hundreds of years ago, would snap clean in half if you tried to bend it today. This recrystallization can be observed non-destructively, using x-ray diffraction to study the crystal structure of the metal; using this technique, it is possible to tell whether a piece of silver was melted and forged in centuries past, or more recently.

However, if you, a private collector, wish to get these tests done on a piece of hacksilver you own, it might prove difficult. Archaeologists don't like collectors, and the machines and databases needed to do these analysis might not be made available for collector use. I know the archaeology department in the university where I work does not let anybody but archaeologists use their XRF/XRD machine.

Great post

I'd just like to add for others not familiar with these tests, Universities with chemistry, metallurgy and/or materials science programs usually have this analytical equipment as well. Many will do outside testing, but they charge a fee.

I use XRD, XRF, and SEM/EDS data frequently in my job and know know the R&D scientists quite well, but doing "personal" analytical work can get them in trouble, so I don't ask.