A root in the Qenya Lexicon of the 1910s glossed “burst asunder” with the derivative ᴱQ. rúvina “burst” (QL/81). G. ruf- “tear” from the contemporaneous Gnomish Lexicon is probably related (GL/66). There are no signs of this root in Tolkien’s later writing, but I think ᴺ√RUB “burst asunder” is worth retaining as a Neo-Root.