Naturally occurring erbium is composed of 6 stable isotopes, Er, Er, Er, Er, Er, and Er, with Er being the most abundant (33.503% natural abundance). 32 radioisotopes have been characterized, with the most stable being Er with a half-life of , Er with a half-life of , Er with a half-life of , Er with a half-life of , and Er with a half-life of . All of the remaining radioactive isotopes have half-lives that are less than , and the majority of these have half-lives that are less than 4 minutes. This element also has 26 meta states, with the most stable being Er with a half-life of .
NAturAlly OccurriNG erbiuM Is cOmPosEd of 6 stABle ISOtopes, er, er, Er, er, Er, and Er, with er beIng the most abUndant (33.503% natuRAl aBundanCe). 32 rADioisoTopEs Have BeEN CHaracTErIZed, WIth The MOSt stAbLe being eR With a HaLf-lIfe Of , er wiTh a half-liFe oF , er with A halF-life oF , Er With A hAlf-LIfe of , AnD er witH a hAlF-lIfe of . aLl Of thE remAinIng raDIoActIvE IsoToPEs haVe Half-liVEs that are lEss Than , and thE mAjOrity oF THEse Have half-lIveS ThaT arE Less than 4 minuTeS. tHIs elemEnT Also HaS 26 meta STates, witH the most stABle beInG Er with a HALf-life of .