( ( ( ( Natural Substances ) : ) ( ( Good but ) Indifferent ) ) ? )
(ROOT (NP (NP (NNP Natural) (NNP Substances)) (: :) (NP (NNP Good) (CC but) (NNP Indifferent)) (. ?)))
Natural Substances: Good but Indifferent?
(ROOT (S (NP (DT A) (NN mineral)) (VP (VBZ is) (VP (VBN described) (PP (IN as) (NP (NP (DT a) (JJ natural) (NN substance)) (SBAR (WHNP (WDT that)) (S (VP (VBZ makes) (PRT (RP up)) (NP (NNS rocks))))))))) (. .)))