Late Pleistocene/Early Holocene Evidence of Prostatic Stones at Al Khiday Cemetery, Central Sudan
Fig 4
SEM backscattered electron images of the microstructure of stone S3: a) outermost portion of the stone, where ovoidal structures occur; b) detail of the ovoids surrounded by a thin shrinkage rim; c) detail of the dense packing of crystals which form micron-sized spheres in some cases with a geode type structure and (on the left) acicular crystals aggregate of apatite; d) micro-fractures crossing the stone, filled by secondary calcite; e-f) micro-pores due to bacterial attack.