Negative ion foda wani nau'i ne na ma'adinai mai mahimmanci wanda aka haɗe shi ta hanyar wucin gadi ko kuma daidaitattun mutane ta hanyar amfani da ka'idar samar da ions mara kyau a cikin yanayi.Gabaɗaya shi ne tourmaline foda + abubuwan lanthanide ko abubuwan da ba kasafai ba.Matsakaicin abubuwan da ba kasafai ake samu a duniya ba ya fi na tourmaline foda da abubuwan da ba kasafai ba.An ƙidaya fiye da 60%.

Mu ion korau foda zai iya saki ion korau da nisa infrared ray.lafiya da halitta.