Echinoderm Calcite: Single Crystal or Polycrystalline Aggregate

Science  01 Sep 1967:
Vol. 157, Issue 3792, pp. 1048-1050
DOI: 10.1126/science.157.3792.1048


Electron microscopy of natural and broken surfaces of echinoid skeletal plates reveals that the interior portions have the morphology of a single crystal, whereas the exterior is a polycrystalline aggregate with preferred orientation. These data help to resolve earlier contradictory x-ray and optical evidence.