ellipsoidile

Ellipsoidile is a descriptive term used in geology and paleontology to refer to small, ellipsoidal bodies embedded within a host rock or sediment. It is not a recognized mineral species or a taxonomic group; rather, it functions as a morphological descriptor applied to discrete inclusions or fossils that approximate an ellipsoid in outline. In petrographic practice, ellipsoidile bodies are typically identified under cross-polarized light or by scanning microscopy, and they may range from tens of micrometers to a few millimeters in length.

Morphology and composition

Ellipsoidile objects may be composed of carbonate, silica, phosphate, iron oxides, organic-rich matter, or a mineral assemblage distinct from the surrounding matrix. Surfaces can be smooth, angular, or show evidence of abrasion; internal structure may be homogeneous, laminated, or contain concentric zoning. The term emphasizes shape rather than a specific mineralogical identity.

Formation and occurrence

Possible origins include diagenetic precipitation around a nucleus, recrystallization textures, or remnants of microfossils preserved in the sediment. They occur in various sedimentary rocks, especially limestones, shales, and dolostones, where suitable chemical conditions exist to promote ellipsoidal growth. The term remains descriptive rather than diagnostic; identifying an ellipsoidile often requires context from petrography and geochemistry.

Etymology and usage

Derived from ellipsoid, with the suffix -ile indicating a diminutive or belonging to; the term is used to differentiate ellipsoidal inclusions from other shapes within a matrix.

See also

Ellipsoid; Concretion; Microfossil; Diagenesis; Petrography.