( Samples ( ( ( ( are ( grouped ( by ( rock type ) ) ) ) and ) ( include ( mineralized ( and ( ore-grade specimens ) ) ) ) ) . ) )
(ROOT (S (NP (NNS Samples)) (VP (VP (VBP are) (VP (VBN grouped) (PP (IN by) (NP (NN rock) (NN type))))) (CC and) (VP (VBP include) (NP (JJ mineralized) (CC and) (JJ ore-grade) (NNS specimens)))) (. .)))
Samples are grouped by rock type and include mineralized and ore-grade specimens.
(ROOT (S (NP (JJ Ores) (NN rock)) (VP (VBZ contains) (NP (NP (NNS concentrations)) (PP (IN of) (NP (JJ valuable) (NNS minerals))))) (. .)))