( ( ( ( ( ( ( ( ( Soft rocks ) , ) ( which ( may ( crumble ( in ( the water ) ) ) ) ) ) , ) and ) limestone ) or ) ( ( other rocks ) ( containing ( mineral ore ) ) ) ) ( ( ( are not ) recommended ) . ) )
(ROOT (S (NP (NP (NP (JJ Soft) (NNS rocks)) (, ,) (SBAR (WHNP (WDT which)) (S (VP (MD may) (VP (VB crumble) (PP (IN in) (NP (DT the) (NN water))))))) (, ,)) (CC and) (NP (NN limestone)) (CC or) (NP (NP (JJ other) (NNS rocks)) (VP (VBG containing) (NP (NN mineral) (NN ore))))) (VP (VBP are) (RB not) (VP (VBN recommended))) (. .)))
Soft rocks, which may crumble in the water, and limestone or other rocks containing mineral ore are not recommended.
(ROOT (S (NP (JJ Ores) (NN rock)) (VP (VBZ contains) (NP (NP (NNS concentrations)) (PP (IN of) (NP (JJ valuable) (NNS minerals))))) (. .)))