The significance of vivianite in archaeological settings

Abstract

Vivianite is a bluish mineral sometimes encountered in archaeological deposits. It is notable for its tendency to change color from white or grayish to blue on exposure to air. Vivianite requires specific conditions for its formation-sources of iron, phosphate, and water, as well as low levels of oxygen and sulfide. Microbial activity is also thought to play a part in vivianite formation. The majority of archaeological texts do not discuss vivianite to any great degree, preventing a more detailed interpretation of site conditions and features. Vivianite was found in 25 exhumed burials from the North Brisbane Burial Ground, Queensland, Australia. Research indicated that bone or tissue samples for DNA analysis are best taken from areas distant from vivianite encrustations and that presence of vivianite has implications for artifact conservation. Vivianite at the North Brisbane Burial Grounds helped protect some skeletal and dental elements, preserved the impressions of metal coffin lacing, and also corroborated the oral history of temporary waterlogging and acted as a measure of pollution levels across the site.

The tattoos of the Tyrolean Iceman: a light microscopical, ultrastructural and element analytical study

“…On some locations of the iceman's skin even blue pustules were found (Tiefenbrunner, 1992) which were interpreted as air oxidized vivianite. Also in other archaeological findings vivianite was described (McGowan and Prangnell, 2006) and it was argued that microbial activity could have played a role in its formation.…”

Purple Staining of Archaeological Human Bone: An Investigation of Probable Cause and Implications for Other Tissues and Artifacts

“…For example, the characteristic deep blue color of hydrated iron phosphate vivianite arises from charge transfer between Fe 2+ and Fe 3+ following conversion of some of the Fe 2+ to Fe 3+ by oxidation in air. This mineral is found in archaeological contexts, requiring sources of iron, phosphate, and water in the presence of low levels of oxygen and sulfur [31]. This would not explain the pink coloration seen, so the presence of vivianite can be discounted as an explanation.…”

Perfect vivianite crystals excavated from a highly sealed ancient tumulus in Jing'an County, Jiangxi Province, China

“…Vivianite is usually found as an authigenic mineral in sedimentary settings under redox/reducing and aqueous conditions, rich in Fe 2+ and phosphate ion (PO 4 3− ). Vivianite is also found with fossils and human remains (Pienpenbrink, 1989;Manning, Murphy, & Prepas, 1991;Deike, Granina, & Callender, 1997;Manning, Prepas, & Serediak, 1999;Walker & Owen, 1999;McGowan & Prangnell, 2006;Zougrou et al, 2014). In this case, after the oxygen for aerobic bacteria to reproduce was soon exhausted within the tightly sealed coffins, an anoxic/reducing condition was built in no time.…”