engleski

The mineralogical characteristics of the Lamboglia 2 Roman-age amphorae from the central Adriatic (Croatia)

The mineralogical characteristics of four Lamboglia 2 Roman-age amphorae excavated from ancient underwater shipwreck localities in the central Adriatic were investigated. X-ray diffraction and optical microscopy analyses showed that the amphorae have similar primary mineral compositions, mainly consisting of quartz, plagioclase, potassium feldspar, diopside, illite and calcite, most probably originating from clayey Eocene flysch deposits used as a raw materials in manufacture. The difference in mineral composition between these samples is recognised from the presence or absence of melilite, high-magnesium calcite, aragonite, gypsum and analcime. It was shown that melilite is a secondary mineral formed during the firing process, while others, which build up through incrustation of marine benthonic communities on the amphora walls and fill the cracks in the amphora bodies, were formed by crystallization in seawather. The firing of the original pieces of amphorae showed that melililte could be formed at temperatures higher than 800°C, most probably through interaction between calcite and silicate minerals present in the raw materials. the presence of melilite, and the absence of illite and calcite, were used to estimate the firing temperature of the amphorae during their production.

Adriatic Sea; Lamboglia 2; amphorae; mineralogy; optical microscopy; X-ray diffraction

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