“Gold corrosion”: An alternative source of red stains on gold coins

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61388980%3A_____%2F21%3A00540290" target="_blank" >RIV/61388980:_____/21:00540290 - isvavai.cz</a>

Alternative codes found

RIV/00216305:26620/21:PU140493 RIV/61989592:15310/21:73609498 RIV/62156489:43210/21:43919332

Result on the web

<a href="https://doi.org/10.1016/j.mtla.2021.101025" target="_blank" >https://doi.org/10.1016/j.mtla.2021.101025</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.mtla.2021.101025" target="_blank" >10.1016/j.mtla.2021.101025</a>

Result language

angličtina

Original language name

“Gold corrosion”: An alternative source of red stains on gold coins

Original language description

Recently, the phenomena of red stains defects was found on historical and modern golden coins around the world. This “Gold corrosion” can be the reason for reduction of coin value, especially of modern high-premium coins. In such modern investment coins, the contamination of the surface by microscopic particles of metallic silver is reported to be a common cause of such stains. Corrosion of these particles (or even back reduction) is associated with a distinct change of colour. In the case of historical coins, this relatively simple explanation does not respond in some cases. The submitted study is dealing with analysis of red stains on of Austro-Hungarian gold ten crowns coins, which served as a common part of circulating currency. They were therefore minted in thousands/million pieces by standard procedures each year. It is therefore quite logical that these coins can have different mechanisms of red spots formation than modern high-premium coins. Red stains on Austro-Hungarian coins were analysed by the means of light (LM) and digital microscopy (DM), energy-dispersive X-ray spectroscopy (EDS), energy dispersive X-ray fluorescence spectroscopy (XRF), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), Mössbauer spectroscopy, X-ray powder micro-diffraction (µ-XRPD) and Raman microscopy. The EDS, XRF and XPS analysis points to the presence of iron and oxygen in red stains, no silver or its corrosion products were detected. The exact determination of red stains was done by µ-XRPD and Raman microscopy where an iron(III) oxide-hydroxide (Goethite) was found as main product.

Czech name

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Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

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OECD FORD branch

10402 - Inorganic and nuclear chemistry

Project

—

Continuities

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2021

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

Materialia

ISSN

2589-1529

e-ISSN

—

Volume of the periodical

15

Issue of the periodical within the volume

MAR

Country of publishing house

DE - GERMANY

Number of pages

8

Pages from-to

101025

UT code for WoS article

000634687500008

EID of the result in the Scopus database

2-s2.0-85100685911