Siliceous spicules and South America precolonical ceramics
Precolonical ceramics are commonly found in South America, particularly, along the Amazon River and report back to approximately 5000 years ago. There is a huge archaeological record and an extensive anthropological interest in retrieving embedded information from the ceramics.
One of the open questions posed by archaeologists, anthropologists and material scientist is: “How these ceramics were built considering their large size and material’s low mechanical properties?”
We have contributed to understanding the role of siliceous spicules as biological South America ceramic reinforcement component. The siliceous spicules, when embedded in the clay matrix, improve clay’s mechanical properties in terms of toughness and improve fracture propagation arrest.
Amazonian expedition 2014: aerial view Drulia spp (cauíxi) - tree sponge
Schematic representation of the ancient Amazonian coil-roll technique used to orient the siliceous spicules (Demospongiae) to enhance the mechanical properties of pottery (e.g. utilitarian’s, cultural expression items).
Preserving ancient ceramic fabrication tradition
(a) Digital image of representative ancient pre-colonial Amazonian potsherd (vase wall, Santa Helena archeological site, N1049 E880, Brazil). (b) Low magnification optical microscopy image showing the presence of glassy structures attributed to siliceous spicules of the freshwater tree sponge Demospongiae Drulia uruguayensis (cauíxi). (c) SEM inspection of the same potsherd showing rod-like structures inside the clay matrix and displaying a preferential orientation. (d) Cross-section in the phase contrast-enhanced μ-tomography 3D data reveals co-alignment of spicules in different regions within the intact bulk of the sample. (e) Averaged image from (d). In both cases the spicules show preferential orientation. (f) SEM image of potsherd showing spicule alignment within the ceramic matrix.
In collaboration with: Museu Paraense Emílio Goeldi (MPEG, Brasil)