Also euhedral. (in a rock) noting or pertaining to a mineral constituent having its own characteristic outward crystalline form unaltered by the other constituents of the rock; automorphic.
having its own characteristic form.
adjective
(of minerals) occurring naturally in the form of well-developed crystals
Calcareous sandstone with idiomorphic calcite and honey-comb
Optical micrographs of idiomorphic quartz. (A) Note the close growth
Igneous textures and structures
Idiomorphic pronunciation and definition – YouTube
a) Pores caused by the dissolution of calcite idiomorphic crystals
The petrographic microphotographs of aplite. A ? idiomorphic quartz