Samples of the summit of the Rio Grande Rise (RGR) were dredged by the Brazilian Geological Survey on board of the Marion Dufresne in 2011. This campaign is part of the de Exploration of the Rio Grande Rise Program (PROERG, in poruguese) that aimed to research the Fe-Mn substrate. Hundereds of decimetric and metric samples of Fe-Mn crusts, carbonate rocks and phosphates were collected by dredge in the West-Central portion of the RGR. The carbonate samples were selected and described macroscopically and then 25 thin sections were made. Percentages of components in the microscopic descriptions were determined using visual estimation charts. The carbonate rocks classification were based on microfacies texture.