Coins and how to properly excavate, publish, and read them

In order to fully comprehend my project, it is first necessary to get a better understanding of how coins are excavated, read, and published. This chapter is also an appeal for “best practices,” as careful excavation, thorough analysis, and complete publication of each coin found at an archaeological excavation would have made a project like this one much easier to accomplish.

Just as in other sciences, work in the field of numismatics requires the highest standards of accuracy. To utilize the maximum potential of coins, they must be analyzed and described with great attention to detail, so that every piece of information can be used for its interpretation.[207] This careful treatment should already start at the excavation site, where the recording of coins should follow the most meticulous standards established to locate and fix the position of a small find. Preferably, coins are measured in according to their X and Y axes, giving their longitude and latitude coordinates as well as according to the Z axis, providing a three-dimensional position. Measuring each coin in the field according to this procedure enables archaeologists on the site as well as future readers of excavation reports to determine the exact find spots of coins, as well as their relative position to each other.[208] This system has recently been successfully used at Horvat Kur, where it enabled the archaeologists to plot each coin on a heatmap, clearly showing clusters of coins in certain parts of the site.[209] Thus, the contexts of coins should always be recorded and the record of the findspot should always travel with the coin. Ideally, the archaeologist will also provide a description of the coin’s context, e.g., a pit, a fill layer, or any other feature that is distinct from the matrix in which the coin was embedded.[210]

Coins found in excavations should be cleaned professionally in a lab. Often, coins are found in very poor physical condition and show clear signs of deterioration, with patches of green copper chloride corrosion or heavy incrustations of silver chloride or copper carbonate.[211] Only a professional laboratory that possesses the right equipment should be allowed to clean the coins: scraping away corrosion in the field will only damage them further. Furthermore, ALL coins should be cleaned: it is impossible to determine in the field which coins will be useful for analysis and which ones will not. Only cleaning the “pretty” coins, like the silver and gold ones, as has often been done in the past, drastically skews the picture of the total assemblage of coins deposited at a site.[212]

After the coins have come back from cleaning, it is up to the numismatist to analyze each one. Unfortunately, different specialists apply different recording methods, picking and choosing which information they deem important enough to document. In addition, there is no universally accepted system for the presentation of coin catalogues, and published records exhibit a range of different lists and schemes.[213] Last, poor publication standards, in which archaeologists only publish coins they believe are “archaeologically significant,” are common, and make comparisons between published sites challenging.[214] Ideally, each numismatist should record and publish coins in a similar fashion, noting all elements that make up a particular coin, to enable comparisons between coins and across sites.[215] Luckily, some standards have been reached of late, and more and more numismatists are publishing their data in a similar way.

Let us now take a closer look at the different elements of a coin, as each element can provide valuable information to the archaeologist, and their information has been used in our statistical analyses. The specific elemental details of each specific coin from this project can be found in the various downloadable Excel-files on the website.

Numismatists use specialized vocabulary to describe the various components that make up a coin.[216] The shaped piece of metal onto which the coin design is imposed is called the blank or flan. The flan is struck with a pair of dies to impose an image on the metal. On the two sides of a coin, the side that bears the portrait is called the obverse (abbreviated to obv.) and the side that bears the type, or design, is called the reverse (abbreviated to rev.).[217] The coin may have an obverse and reverse written inscription, or legend.[218] Included with the reverse legend, which often describes the coin type or issuing authority, may be letters or figures in the field of the coin, that is, the space between the main image and the legend: the fieldmarks.[219] The reverse image is often set above a horizontal groundline, which creates a small lunate space at the bottom of the coin. This space is called the exergue, and may be occupied by a date or a mintmark: an abbreviation of the place where the coin was minted.[220] Additionally, the mintmark may be followed by an indication of the workshop where the coin was minted, called the officina. The officina on Roman coins is usually indicated by a Greek letter (Α, Β, Γ, Δ, etc.).[221]

Sometimes, things went wrong during the minting process as ancient coins were hand struck and mistakes happened easily. Occasionally, a new coin was struck on a pre-existing one instead of on a new blank: this is called an overstrike.[222] Not to be confused with this process is one in which more than one attempt was made to strike a coin and where the die shifted across the face of the blank between blows, creating a double-struck coin (or a double-strike)[223]. Additionally, some coins show signs of graffiti; letters or symbols scratched into the fields of the coin after its creation.[224] Last, coins sometimes were re-used as amulets: the user would pierce a hole through the coin to use as a pendant on a necklace or bracelet.[225]

Most ancient coins were made of one of three metals: bronze, silver, or gold.[226] Coinage was nominally tri-metallic, though by the fifth century the production of silver coins in the West had mostly declined to ceremonial issues.[227] Normally in describing coins in prose, English terms are used for the predominant metal in the coin. Catalogues, on the other hand, almost universally employ abbreviations either taken directly from the periodic table or from Latin terms. Thus, AV (aurum) stands for a gold coin, AR (argentum) for a silver coin, and AE (aes) for a bronze or copper coin.[228] In antiquity, the only way of stabilizing a definite exchange value to money was to strike a coin to a specific weight and to regulate its alloy.[229] In other words, the tariff or exchange value of a coin was related directly to the amount of precious material that went into the coin: the coin had an intrinsic value.[230] Coins within a certain series and denomination all had the same weight (at least, in theory). Thus, by weighing a coin, it is sometimes possible to determine to what series it belonged and when it was minted.[231] Today it is customary to register coin weights in grams, and for the past decades, scholars have attempted to compile lists of coin series and their corresponding weights in grams. Next to the weight, many catalogues also note the size of the coin. This is sometimes called the module.[232] The size is generally given in millimeters and describes the diameter of the coin. When the coin is not completely round, two numbers may be given (the shortest and longest diameter of the coin) or only the maximum diameter is indicated.[233] In numismatics there are four categories of sizes, each given a specific number. Coins over 25 mm are given the number 1, coins between 21 and 25 mm are category 2, coins between 17 and 21 mm category 3, and coins smaller than 17 mm category 4. So, a bronze coin of 10 mm would be abbreviated as an AE4 coin.[234] Here as well, studies have tried to link the sizes of coinages to certain coin types, often connected to die-studies.[235] Last, numismatists indicate the axis of the coin: how the obverse and reverse side of a coin relate to one another in reference to their rotation. This can be noted in three ways, either by using arrows, or by numbers of a clock, or by degrees from 0 to 360. Arrows give a visual representation of the axis: for example, ↓ means that when looking at the obverse side of the coin, the front will be in upright position, while the back of the coin will be upside down. This same position can be written as 6 o’clock or as 180°. The material of the coin as well as its size, weight and often axis can identify the denomination: a term indicating the coin’s specific value (for example, solidus, tremissis, semissis, denarius, nummus, etc.).[236]

One important complication is that excavated coins typically show a lot of “wear,” meaning the surfaces and edges have been smoothed due to extensive handling or use. The wear on a coin can imply either a long period of circulation or a shorter period of circulation at a higher intensity.[237] Bronze coins in particular are made of a softer material than silver and gold and therefore are more susceptible to this deterioration. One result of this wear is that the coin pieces become smaller over time and lose some of their weight (and are harder to read). Hence, measuring and weighing a coin might not tell us anything about the series to which this coin belonged but might provide a clue about the handling of the coin. For example, if we know the minting size and weight of the coin through its legend and mintmarks, we can calculate how worn it is, and thus how new or used the coin was before it was deposited.

All these pieces of information must be recorded by the numismatist to provide a complete picture of the coin.[238] Each element can teach us something about the history of that coin, its value, and its circulation. Together they lead the numismatist to the final step: the dating of the coin. Often coin catalogues in excavation reports arrange the published coins according to date, starting with the oldest coins and working their way up the youngest. For clarity, the coins are further ordered in clusters according to the emperor who was responsible for their minting. Thus, although trying to pinpoint an exact minting date for a coin is often the last step, it is the determining factor for the presentation of coins in publications.[239]

When publishing a coin catalogue, the locus and basket numbers for each coin should also be provided, with an explanation of the archaeological context. Plans and maps should accompany these lists, indicating which parts of the building were excavated, enabling readers to pinpoint the find spot of each coin within the building. Only when all these elements are fully described for each coin does it become possible for future scholars to compare deposits found within the same building and between different buildings, as would be needed for a project like this one. However, as the reader might have already guessed, most of these practices are not being systematically applied by scholars in the field. Below, I will go over some obstacles that archaeologists and numismatists commonly encounter when digging and analyzing coins, as well as some of the consequences these problems might have for future scholars, and how I have tried to overcome these shortcomings in this particular project.


[207] It is first necessary to stipulate what we mean by the word “coin”. Merriam-Webster defines a coin as “A piece of metal (or, rarely, of some other material) certified by a mark or marks upon it to be a definite exchange value, and issued by governmental authority to be used as money; also, such pieces collectively.” The classic source for all numismatic vocabulary is F. von Schrötter Wörterbuch der Münzkunde. In English there are the A.R. Frey Dictionary of Numismatic Names and R.G. Doty The Macmillan Encyclopedic Dictionary of Numismatics (American Numismatic Society Website, Introduction to Numismatic Terms and Methods, footnote 2). For this project, a coin is any piece of flat, rounded metal that seemed to have been used for economic exchange, whether it has certified marks on it or is a blank flan.

[208] This, of course, is essential in this study: for example, it is vital that we know if coins were found on, in, or under the floor. Any change in position has severe consequences for our interpretation of the function of specific coins.

[209] This has turned out to be crucial for our understanding of the coins at Horvat Kur: because of the heatmaps, we were able to see patterns in how the coins were dispersed over the surface of the portico. Recording like this could thus be crucial for our future understanding of ancient synagogue coins.

[210] Casey 1986, p. 144. That this high standard of excavation is frequently not adhered to is evident. Archaeological work methods differ from site to site, and sometimes even from year to year, depending on who is in charge, and how much time and budget there is available in any given season. Discrepancies in quality between certain excavations will also be apparent in this project.

[211] For an overview of the deterioration processes on metals, see Schiffer 1987, pp. 189–197.

[212] This is also a problem in this study; sometimes an excavation project does not have the budget to clean all the coins and a selection needs to be made based on a first visual assessment. In theory, for example, until the last coin of an assemblage is cleaned, one can always argue that the closing date given to a specific deposit is not final, and that a later coin can be present within the group of unidentified coins (a point also made by Ahipaz 2015, p. 11).

[213] For example, some numismatists choose to list and summarize assemblages by emperor or minting place, while others arrange their coins chronological by minting date. Most catalogues do not mention coin sizes or weights, or the coins are assigned to a minting place and emperor but do not give an exact date. Consequently, this makes comparing excavating assemblages time consuming and frustrating. The availability of published coin lists and the method of presenting the material determines what we can say about them: we should thus strive to have as much consistency as possible between excavation reports. For more recommendations on publishing coins, see Duyrat 2016b.

[214] As we will also see in the analysis of our coin deposits (see below).

[215] Often limitations in space in the publication report cause the numismatic report to be very brief or incomplete. With the convenience of the internet, however, this could be a thing of the past. Some excavations have already chosen to publish their full coin catalogue on the internet, either for free or with a password (for example, the Caesarea synagogue coin catalogue at:

[216] For further details and examples on coin reading, see Casey 1986, pp. 146–153; Grierson 1975, pp. 72–123; Howgego 1995, pp. 26–35; and American Numismatic Society Website: Introduction to Numismatic Terms and Methods.

[217] Jones 1990, pp. 224–225. It is impossible to categorize the great variety of coin types in one satisfactory manner. Some series of coins show the ruling emperor, which makes it easier to date the coin, while others depict city gods and goddesses, or illustrate specific events. Often catalogues refer to coins by an agreed–upon abbreviation for the type. For example, the “fallen horsemen”–type coin refers to one of the most common series of Roman coins minted in the middle of the 4th century CE, depicting men falling off their horses. For an overview of figures depicted on the reverse side of Roman coins, see Klawans 1959, pp. 37–100.

[218] Jones 1990, pp. 162–164. Coins often served as propaganda for the imperial state, and their complexity of design could exceed the minimum elements required for simple identification. Thus, a separate field of numismatics has developed over time that approaches coins from an art historical point of view. This approach reads the iconic language of coinage following the same theoretical procedures as reading verbal language: the images are coded and communicate a certain meaning to its user; the image as a sentence. Examples of scholarship on coins as art historical objects are; Howgego 1995, pp. 75–77; Elkins and Krmnicek 2014; Elkins 2017; Caccamo Caltabiano, 2018; Noreña 2018; Stewart 2018.

[219] The field is often further subdivided into a left and right side. In publications “to l.” and “to r.” refer to the left side and to the right side of the field, as the viewer sees it. When, on the other hand, the l. arm or the r. arm of a figure are described, this refers to the left arm or right arm of the figure itself. Some catalogues use a graphic technique to avoid this confusion. For example: A|* refers to an A in the left field and an * in the right field (see examples in the catalogue). The items that are held by the figures are often called attributes or adjuncts. Examples are a scepter, a snake, a branch, etc. In general, when describing a coin, an author moves from left to right, from top to bottom.

[220] Jones 1990, pp. 190–192. The word exergue derives from ex argon, or literally “outside the (main) work.” A mintmark frequently found in Israel, for example, is CONOB: Con(stantinopoli) ob(ryziacus), “fine gold solidus of Constantinople”. The letters OB refer to the number 72, that is, the number of gold solidi struck to the weight of one pound.

[221] Jones 1990, pp. 225–226.

[222] Jones 1990, pp. 229–230.

[223] Jones 1990, p. 103.

[224] Jones 1990, p. 129.

[225] Written sources indicate that the use of coins as amulets was popular in Late Antiquity. For example, John Chrysostom warned against “wearing bronze coins of Alexander of Macedon as amuletic bracelets and anklets” (Maguire 1997, p. 1040; John Chrysostom, 52). This phenomenon will be explored in more detail in “SYNAGOGUE COIN DEPOSITS: THE FLOOR DEPOSITS”.

[226] The material from which a coin was produced needed to be abundant enough to provide the raw material for an exchange medium, but scarce enough to have value in its own right. The selection varied from culture to culture. For example, in India the metal of choice was silver whereas in China it was copper. The earliest coins found in the West, which were minted in western Asia Minor in the mid- to late seventh century BCE, were of electrum, a naturally-occurring alloy of gold and at least 20 per cent silver. It was not until the reign of Philip II, the father of Alexander the Great, that gold coins became common (American Numismatic Society Website).

[227] Grierson 1999, pp. 12–13; Guest 2012, p. 105. This might explain why we do not have any examples of silver coins found under the floors of synagogues (see “SYNAGOGUE COIN DEPOSITS: THE FLOOR DEPOSITS”).

[228] See Jones 1990, pp. 8–9, 24–25, 31. Although there is a difference between copper (a pure material found in nature) and bronze (an alloy of copper and tin), the difference between the two materials in coins is difficult to distinguish with the naked eye. Therefore, numismatists historically have used the terms interchangeably. Only in recent years with advanced chemical analysis like spectroscopy or irradiation, has it been possible to determine with any degree of precision the exact metals of which a coin is composed. Perhaps in the future the general terms AV, AR, and AE will be replaced by more exact scientific descriptions of the coin’s content (see King, Metcalf, and Northover 1992, who found a wide diversity of different alloys among the same mints).

[229] American Numismatic Society Website, Vocabulary.

[230] In comparison to modern currency that has an extrinsic value; the worth of a certain coin or paper bill is set by the government and dependents on the stock market and exchange rates.

[231] It is important to note that the weight standard of an issue is the weight of the unit of which the various denominations produced are fractions or multiples. In Late Antiquity, most standards were based on the siliqua: a silver unit of 3.4 grams. A gold solidus was worth 24 siliquae, while a golden semissis was half a solidus and thus worth 12 siliquae (Jones 1990, pp. 289–290).

[232] Jones 1990, p. 199.

[233] In this project, I have chosen to give only the average diameter of a coin. Providing one number per coin makes comparison between coins easier and statistical analyses more feasible.

[234] These abbreviations are mostly used for small bronze coins for which we don’t have specific denominations. They are the most common coins found in ancient synagogues.

[235] For example, Bland 2018a.

[236] See also Sperber 1974. A good resource to look up coin denomination is; a digital representation of numismatic concepts according to the principles of Linked Open Data, established by a wide community of numismatic scholars and institutions.

[237] It is thought, for example, that worn coins of the first century CE were in circulation for a prolonged period as suggested by countermarks or graffiti of the second and third century CE on these coins (Evans DeRose 2018, p. 6) There is no accurate way of assessing how many years of circulation the degree of wear on a coin indicates. Numismatists have tried to use the weights of discovered groups of coins to construct tables of frequency, comparing the worn group to a group of newly issued pieces and assessing the differences (Crawford 1983, pp. 204–205).

[238] A good introduction to reading and dating coins is Klawans Z, 1959, Reading and Dating Roman Imperial Coins.

[239] Crawford established eight different considerations for dating a coin and appraising its minting place; see Crawford 1983, pp. 189–190.