Talk:Mining/@comment-92.75.206.12-20171020215004/@comment-24.185.93.214-20171029041116

Anon2, it is indicated in-game

A rare Eidolon gem, created from the fossilized blood of an ancient Sentient. - Sentirum

A rare local gem, formed when the gas known as Breath of Eidolon becomes trapped in molten iradite. - Nyth

I think it is safe to say a crystal formed out of a piece of an eidolon is an eidolon crystal(gem).