Onion morphology and microstructure of polyhedral serpentine

We describe the shape and internal structure of polyhedral spheroids found in serpentinized periclotites. Serpentine spheroids resemble geodesicdomes madeof similar to 160 to 180 triangular facets. At facet edges, the nested layers bend by similar to 14 degrees along their three < 010 > crystallographic directions, resulting in an onion-like structure with lateral continuity of the layers. The stacking of the serpentine layers within sectors is controlled by interlayer bonding. These polyhedral onions correspond to a novel type of spherical nanostructure for layered materials.