▁and ▁eye . ▁Despite ▁being ▁less ▁common ▁than ▁most ▁gar net s , ▁it ▁is ▁a ▁widely ▁used ▁gem stone ▁with ▁numerous ▁alternative ▁names , ▁some ▁of ▁which ▁are ▁mis nom ers . ▁Chrome ▁py ro pe , ▁and ▁Boh em ian ▁gar net ▁are ▁two ▁alternative ▁names , ▁the ▁usage ▁of ▁the ▁latter ▁being ▁disc ou rag ed ▁by ▁the ▁Gem ological ▁Institute ▁of ▁America . ▁Mis nom ers ▁include ▁Colorado ▁ruby , ▁Arizona ▁ruby , ▁California ▁ruby , ▁Rock y ▁Mountain ▁ruby , ▁El ie ▁Ruby , ▁Boh em ian ▁car b un cle , ▁and ▁Cape ▁ruby . ▁ ▁The ▁composition ▁of ▁pure ▁py ro pe ▁is ▁M g 3 Al 2 ( Si O 4 ) 3 , ▁although ▁typically ▁other ▁elements ▁are ▁present ▁in ▁at ▁least ▁minor ▁proport ions — th ese ▁other ▁elements ▁include ▁Ca , ▁Cr , ▁Fe ▁and ▁M n . ▁Py ro pe ▁forms ▁a ▁solid ▁solution ▁series ▁with ▁al m and ine ▁and ▁sp ess art ine , ▁which ▁are ▁collect ively ▁known ▁as ▁the ▁py ral sp ite ▁gar net s ▁( py ro pe , ▁al m and ine , ▁sp ess art ine ). ▁Iron ▁and ▁mang an ese ▁substitute ▁for ▁the ▁mag nes ium ▁in ▁the ▁py ro pe ▁structure . ▁The ▁result ant , ▁mixed ▁composition ▁gar net s ▁are ▁defined ▁according ▁to ▁their ▁py ro pe - alm and ine ▁ratio . ▁The ▁semi - pre cious ▁stone ▁rh od ol ite ▁is ▁a ▁gar net ▁of