( Abrasives ( ( are ( ( ( either ( naturally occurring ) ) or ) ( synthetic minerals ) ) ) . ) )
(ROOT (S (NP (NNS Abrasives)) (VP (VBP are) (NP (NP (DT either) (ADJP (RB naturally) (VBG occurring))) (CC or) (NP (JJ synthetic) (NNS minerals)))) (. .)))
Abrasives are either naturally occurring or synthetic minerals.
(ROOT (S (NP (DT A) (JJ synthetic) (NN diamond)) (VP (VBZ is) (RB not) (VP (VBN considered) (NP (DT a) (NN mineral)) (SBAR (IN because) (S (NP (NNS minerals)) (VP (MD must) (VP (VB be) (VP (VBN created) (ADVP (RB naturally))))))))) (. .)))