DOI article:
Miazga, Beata; Paszkiewicz, Boris: The metal content of selected Polish and Brandenburg coins from the 14th and 15th centuries
DOI Page / Citation link:https://doi.org/10.11588/diglit.49247#0159
THE METAL CONTENT OF SELECTED POLISH AND BRANDENBURG COINS...
coin can once again be “artificially” enriched with a metal that is more precious,
e.g. silver in the example of silver-copper coins discussed above.60
The processes described here show that it is necessary to examine the interior of
a coin, for it is the inside of a coin that comes closest to the original alloy, called the
minting standard. This effect can be attained in two ways. The first is by using very
exact analytical methods, which are called invasive methods, for they examine samples
taken from the coin61 or affect the analyzed object in a way that is noticeable with the
naked eye (e.g. LA-ICP-MS).62 However, in many situations we will not be allowed
to leave a lasting mark on the artefact. When this is the case, what remains is for us
to use physical-chemical methods of analysis, which are less sensitive but also non-
destructive. One such method might be to measure the density of the material from
which the coin was created by using the law of Archimedes.63 The measure of density
that is attained allows us to determine what the main components of the alloy are,
e.g. gold, silver, or copper. Spectroscopic methods are popular non-invasive tools,
including X-ray microanalysis or X-ray fluorescence spectrometry.64 These methods
are usually characterized by a lower degree of penetration;65 as a result, they are used
to examine the surface of artefact. This can be dealt with by just taking a few steps
to prepare the objects for examination, i.e. by delicately cleaning a particular area
on the artefact, but doing so in the least visible way, for example by polishing the
coin’s edge.66 We are in a better situation when it comes to damaged artefact, and this
includes coins, for here it is possible to examine the exposed areas. These spots exhibit
a composition that is usually closer to the original alloy. It is also important to take into
account the size of the examined artefact. When it comes to coins, preparing the side
edge or the exposed area usually provides us with an area of a few millimeters in length
and a few tenths of a millimeter in width. In Print 1, we can see the exposed areas on
three pennies, together with their measurements. The exposed areas that were attained
by way of polishing only have a thickness of 0.3 mm, which makes it very difficult
to measure them. When examining coins using XRF spectrometry, the diameter of
the radiation beam that is made use of depends on the spectrometer model. The new
60 MIAZGA2015.
61 LA NIECE 1998: 114-133; BORGES ct AL. 2017.
62 The laser that results in the evaporation of the sample in the LA-ICP-MS system of measurement has
beams of different diameters, which results in the creation of craters with different sizes on the surface of the
examined artefacts. Their size can be about 0.1 mm (http://www.nhm.ac.uk/our-science/departments-and-staff/
core-research-labs/imaging-and-analysis-centre/esi-new-wave-nwrl 93.html). This was shown using pictures, but
unfortunately without a scale, in a work by B. Wagner (2016).
“ODDY 1998: 147.
64 DEL HOYO-MELENDEZ ct AL. 2015.
65 Excepting neutron activation analysis, which can penetrate deep into the artefacts, as reported by Williams
ct al. (2016) and Akyuz ct al. (2012).
66 LA NIECE 1998: 117.
.155
coin can once again be “artificially” enriched with a metal that is more precious,
e.g. silver in the example of silver-copper coins discussed above.60
The processes described here show that it is necessary to examine the interior of
a coin, for it is the inside of a coin that comes closest to the original alloy, called the
minting standard. This effect can be attained in two ways. The first is by using very
exact analytical methods, which are called invasive methods, for they examine samples
taken from the coin61 or affect the analyzed object in a way that is noticeable with the
naked eye (e.g. LA-ICP-MS).62 However, in many situations we will not be allowed
to leave a lasting mark on the artefact. When this is the case, what remains is for us
to use physical-chemical methods of analysis, which are less sensitive but also non-
destructive. One such method might be to measure the density of the material from
which the coin was created by using the law of Archimedes.63 The measure of density
that is attained allows us to determine what the main components of the alloy are,
e.g. gold, silver, or copper. Spectroscopic methods are popular non-invasive tools,
including X-ray microanalysis or X-ray fluorescence spectrometry.64 These methods
are usually characterized by a lower degree of penetration;65 as a result, they are used
to examine the surface of artefact. This can be dealt with by just taking a few steps
to prepare the objects for examination, i.e. by delicately cleaning a particular area
on the artefact, but doing so in the least visible way, for example by polishing the
coin’s edge.66 We are in a better situation when it comes to damaged artefact, and this
includes coins, for here it is possible to examine the exposed areas. These spots exhibit
a composition that is usually closer to the original alloy. It is also important to take into
account the size of the examined artefact. When it comes to coins, preparing the side
edge or the exposed area usually provides us with an area of a few millimeters in length
and a few tenths of a millimeter in width. In Print 1, we can see the exposed areas on
three pennies, together with their measurements. The exposed areas that were attained
by way of polishing only have a thickness of 0.3 mm, which makes it very difficult
to measure them. When examining coins using XRF spectrometry, the diameter of
the radiation beam that is made use of depends on the spectrometer model. The new
60 MIAZGA2015.
61 LA NIECE 1998: 114-133; BORGES ct AL. 2017.
62 The laser that results in the evaporation of the sample in the LA-ICP-MS system of measurement has
beams of different diameters, which results in the creation of craters with different sizes on the surface of the
examined artefacts. Their size can be about 0.1 mm (http://www.nhm.ac.uk/our-science/departments-and-staff/
core-research-labs/imaging-and-analysis-centre/esi-new-wave-nwrl 93.html). This was shown using pictures, but
unfortunately without a scale, in a work by B. Wagner (2016).
“ODDY 1998: 147.
64 DEL HOYO-MELENDEZ ct AL. 2015.
65 Excepting neutron activation analysis, which can penetrate deep into the artefacts, as reported by Williams
ct al. (2016) and Akyuz ct al. (2012).
66 LA NIECE 1998: 117.
.155