The diagenetic replacement (see diagenesis) of a mineral by a different crystal form of the same mineral. In limestones neomorphism often results in the replacement of calcite by coarser calcite crystals, e.g. micrite may become neomorphically replaced by microspar (4–10 μ‎m crystals), or pseudospar (10–50 μ‎m crystals). Neomorphic spar is characterized by irregularly shaped crystals, often patchily developed, and passing gradationally into unaltered areas.