SILVA, SIDNEY daFAULIN, GUSTAVOZAMARIOLLI, LUISSOUZA, PEDROPRADO, FELIPEWETTER, NIKLAUS2026-03-112026-03-112025SILVA, SIDNEY da; FAULIN, GUSTAVO; ZAMARIOLLI, LUIS; SOUZA, PEDRO; PRADO, FELIPE; WETTER, NIKLAUS. Differentiation of clay content in soil samples containing clay, silt, and sand using the speckle methodology. <b>Brazilian Journal of Physics</b>, v. 55, n. 5, p. 1-10, 2025. DOI: <a href="https://dx.doi.org/10.1007/s13538-025-01843-5">10.1007/s13538-025-01843-5</a>. Disponível em: https://repositorio.ipen.br/handle/123456789/49419.0103-9733https://repositorio.ipen.br/handle/123456789/49419This study aimed to assess the textural differences in soil samples with varying percentages of clay relative to sand content. Speckle interferometry by reflection technique was used, with the aid of polarizers to increase contrast. The method was based on elements of the Time History Speckle Pattern (THSP) and Error Theory. The data consisted of videos of static and dynamic interference patterns observed on the surfaces of the soil samples. These videos were then divided into frames to create THSP files, which formed the basis for constructing the graphs that present the average relative intensities of the interference patterns over time. Quantitative results revealed that samples with higher clay content presented higher mean relative intensities compared to samples with lower clay content. The uncertainties associated with these measurements were 3.6% for the more clayey sample and 4.1% for the less clayey sample. The percentage differences between the average relative intensities were (2.39 ± 0.36) × 10−1 for the highest clay percentage sample and (3.39 ± 0.41) × 10−2 for the lowest clay percentage sample.1-10engopenAccessArtigo de periódico55510.1007/s13538-025-01843-5https://orcid.org/0000-0002-9379-953049.653.00