op ite ▁in ▁this ▁association ▁is ▁a ▁primary ▁ igne ous ▁min eral ▁present ▁because ▁of ▁the ▁depth ▁of ▁mel ting ▁and ▁high ▁v apor ▁press ures . ▁ ▁Ul tr am af ic ▁rocks ▁Ph log op ite ▁is ▁often ▁found ▁in ▁association ▁with ▁ul tr am af ic ▁intr us ions ▁as ▁a ▁secondary ▁alter ation ▁phase ▁within ▁met as om atic ▁marg ins ▁of ▁large ▁layer ed ▁intr us ions . ▁In ▁some ▁cases ▁the ▁ph log op ite ▁is ▁considered ▁to ▁be ▁produced ▁by ▁aut ogen ic ▁alter ation ▁during ▁cool ing . ▁In ▁other ▁instances , ▁met as om at ism ▁has ▁resulted ▁in ▁ph log op ite ▁formation ▁within ▁large ▁volumes , ▁as ▁in ▁the ▁ul tr am af ic ▁mass if ▁at ▁Fin ero , ▁Italy , ▁within ▁the ▁I v rea ▁zone . ▁Trace ▁ph log op ite , ▁again ▁considered ▁the ▁result ▁of ▁met as om at ism , ▁is ▁common ▁within ▁co arse - gra ined ▁per id ot ite ▁x en ol ith s ▁carried ▁up ▁by ▁k im ber l ite , ▁and ▁so ▁ph log op ite ▁appears ▁to ▁be ▁a ▁common ▁trace ▁min eral ▁in ▁the ▁upp erm ost ▁part ▁of ▁the ▁Earth ' s ▁mant le . ▁Ph log op ite ▁is ▁encountered ▁as ▁a ▁primary ▁ igne ous ▁phen oc ry st ▁within ▁l am pro ites ▁and ▁l am pro phy res , ▁the ▁result ▁of ▁highly ▁fluid - rich ▁m elt ▁compos itions ▁within ▁the