▁~ 7 0 % ▁py ro pe ▁composition . ▁ ▁The ▁origin ▁of ▁most ▁py ro pe ▁is ▁in ▁ul tr am af ic ▁rocks , ▁typically ▁per id ot ite ▁from ▁the ▁Earth ' s ▁mant le : ▁these ▁mant le - der ived ▁per id ot ites ▁can ▁be ▁attributed ▁both ▁to ▁ igne ous ▁and ▁met am orph ic ▁processes . ▁ ▁Py ro pe ▁also ▁occurs ▁in ▁ult ra high - press ure ▁( U HP ) ▁met am orph ic ▁rocks , ▁as ▁in ▁the ▁D ora - M ai ra ▁mass if ▁in ▁the ▁western ▁Al ps . ▁In ▁that ▁mass if , ▁nearly ▁pure ▁py ro pe ▁occurs ▁in ▁cry st als ▁to ▁almost ▁ 1 2   cm ▁in ▁diameter ; ▁some ▁of ▁that ▁py ro pe ▁has ▁inclus ions ▁of ▁co es ite , ▁and ▁some ▁has ▁inclus ions ▁of ▁en stat ite ▁and ▁sa pp h ir ine . ▁ ▁Py ro pe ▁is ▁common ▁in ▁per id ot ite ▁x en ol ith s ▁from ▁k im ber l ite ▁pip es , ▁some ▁of ▁which ▁are ▁diam ond - b ear ing . ▁Py ro pe ▁found ▁in ▁association ▁with ▁diam ond ▁commonly ▁has ▁a ▁Cr 2 O 3 ▁content ▁of ▁ 3 – 8 %, ▁which ▁im parts ▁a ▁distinct ive ▁vio let ▁to ▁deep ▁pur ple ▁colour ation ▁( o ften ▁with ▁a ▁green ish ▁t inge ) ▁and ▁because ▁of ▁this ▁is ▁often ▁used ▁as ▁a ▁k im