ʻ i . ▁ ▁An cient ▁P rec amb rian ▁bas al ts ▁are ▁usually ▁only ▁found ▁in ▁fol d ▁and ▁thrust ▁bel ts , ▁and ▁are ▁often ▁heavily ▁met am orph osed . ▁These ▁are ▁known ▁as ▁green stone ▁bel ts , ▁because ▁low - grade ▁met am orphism ▁of ▁bas alt ▁produces ▁ch lor ite , ▁act in ol ite , ▁e pid ote ▁and ▁other ▁green ▁min er als . ▁ ▁L un ar ▁and ▁Mart ian ▁bas alt ▁▁ ▁The ▁dark ▁areas ▁visible ▁on ▁Earth ' s ▁moon , ▁the ▁lun ar ▁mar ia , ▁are ▁pla ins ▁of ▁flo od ▁bas alt ic ▁la va ▁flows . ▁These ▁rocks ▁were ▁sample d ▁by ▁the ▁man ned ▁American ▁Apol lo ▁program , ▁the ▁robot ic ▁Russian ▁L una ▁program , ▁and ▁are ▁represented ▁among ▁the ▁lun ar ▁meteor ites . ▁ ▁L un ar ▁bas al ts ▁differ ▁from ▁their ▁Earth ▁counter parts ▁princip ally ▁in ▁their ▁high ▁iron ▁contents , ▁which ▁typically ▁range ▁from ▁about ▁ 1 7 ▁to ▁ 2 2 ▁w t % ▁Fe O . ▁They ▁also ▁possess ▁a ▁wide ▁range ▁of ▁tit an ium ▁concentr ations ▁( present ▁in ▁the ▁min eral ▁il men ite ), ▁r anging ▁from ▁less ▁than ▁ 1 ▁w t % ▁Ti O 2 , ▁to ▁about ▁ 1 3 ▁w t . %. ▁Trad itionally , ▁lun ar ▁bas al ts ▁have ▁been ▁class ified ▁according ▁to ▁their ▁tit an ium ▁content , ▁with ▁classes ▁being ▁named ▁high