mineraloid
/ˈmɪn(ə)rəlɔɪd/ /ˈmɪn(ə)r(ə)lɔɪd/Mineralogy
noun
A naturally occurring substance which differs from a true mineral in some respect, especially in having an amorphous rather than a crystalline structure.
Origin
Early 20th century. From German Mineraloid from Mineral + -oid.