Examples of veinlets (thickness 0, 05-5 mm) from the Triassic-Lower Cretaceous of the Carpathian orogenic belt are presented and arranged into a provisional system. Several types of recrystallization veinlets are described: (1) Originated by aggrading neomorphism (formed by pseudosparite) with fossils or their ghosts in the filling or with enclosures in the rows ("dashed veinlets" formed by coalescence of parallel veinlets), (2) Originated by removing impurities without disturbing the original granularity, (3) Originated by degrading neomorphism (granulation veinlets formed by pseudomicrite). Intersection of structures, colour of calcite and pressure twinning may be used to determine age relationship. Calcite veinlets order than silicification were barriers for migrating silica colloids (e.g. determined shape of chert concretions). Those contemporaneous with accumulation of silica gels resulted in the "pearl-string" type.