Summary: Fibres of hematite in kidney ore are elongated at right angles to the c-axis. The fibre axis, which may be normal to a face of either of the hexagonal prisms {101¯0} or {112¯0}, may show an abrupt change of orientation along the length of a fibre. There is little preferred orientation around the length of the fibres.

It is confirmed that in some calcite satin spar the fibres are elongated parallel to an edge of the cleavage rhombohedron; in other fibrous growths the elongation is either parallel to or Perpendicular to c.