Skeletal Microstructure of Paleozoic Stromatoporoids and its Mineralogical Implications

The skeletal tissue of 25 specimens examined with the scanning electron microscope is distinguishedfrom the calcite cementfilling the galleries by a finer crystal mosaic and micrometer- and submicrometer-sized cavities. These cavities correpond to the opaque "specks" observed in the light microscope at lower mag- nifications. At higher magnifications in the light microscope and in the scanning electron microscope they appear to be fluid inclusions in the calcite and some have rhombohedral outlines. None of the specimens from a wide range of ages and locations clearly shows remnants of fibrous or spherulitic microstructure, although all have well-preserved macrostructure. In species of cellular microstructure the texture of the cellules is like that of the galleries and suggests that the cellules were originally voids in the skeletal tissue about 10 micrometers across.