Abstract: The ohispherites, are characterized by their associationwith the serpentinites. These roumded inclusions of an avarage diameterof 5-15 centimeters are to be considered as the result of the fragmentation of pre-existing diabase dikes affected by a subsequent differential chlontizatiom. They are generally formed by an external a centralzone exhibiting a distinctily different mineralogical, chemical composition.The chloritization, the Resulting concentric zonation of theseophispherites in due to the circulation of magnesium-rich water solutions.These meta-somatic processes took place in the two following stages:1) In a first stage only the plagioclase is transformed in chlorite(pennine). As calcium, silicon are removed from the plagioclas, secondary clinozoisite, some zoisite are formed.2) Subsequently, the amphibole, a magnesian member of the ferroactinolitetremolite series, is changed in chlorite (clinochlore).The intensity of chloritization varies considerably from one ophispherite to another. It can be explamed by the variation of pressure, temperature conditions, the velocity of the circulating aqueous solutions,the texture of the primary rock, its mineralogical composition as well asthe size of the fragments of pre-existing diabase dykes.