Spectroscopic and ancient geomagnetic field intensity studies on archaeological pottery samples, India

Abstract

Spectroscopic and paleointensity studies have been performed on archaeological pottery samples from Mayiladumparai, Tamilnadu, India. The clay mineral type and its level of structural deformation due to firing were studied from their Fourier Transform Infrared (FTIR) Spectra. The maximum firing temperature attained during baking, firing conditions (open / reduced atmospheric) and iron mineral phase changes were well established. Intensive rock magnetic properties on these samples were carried out in order to select the samples for paleointensity measurements. The results showed that all the samples were magnetically enhanced having superparamagnetic grains with Curie temperature of magnetite (580• C) and yielded mean paleointensity value of 48.71±0.16 µT.

Handmade Traditional Kiln Clay Bricks from Tamilnadu, India: Mineralogy, Temperature Effect and Mechanical Analysis

“…A broad and very strong asymmetry band centered at 1030 cm -1 indicates that the type of clay is red [16]. The presence of weak band at 775 cm -1 coupled with 695 cm -1 is attributed to the presence of quartz [17,18]. The presence of sufficient amount of quartz makes the clay to be self-tempered.…”

The use of mineral magnetic parameters to characterize archaeological artifacts

“…As no single method can provide complete and accurate information on the mineral magnetic properties of the sample, several techniques have been used in this study. The type of magnetic minerals (remanence carriers), their concentration, and domain states are important factors in determining the reliability of the results found in the artifacts [1][2][3][4]. The artifacts are subjected to rock magnetic studies like magnetic susceptibility (frequency) and isothermal remanent magnetisation (IRM) acquisition in order to characterise the main magnetic phases and to select the most suitable samples for paleointensity measurements.…”