( ( Have ( difficulty ( in ( describing ( ( the properties ) ( of ( minerals ( and ( rock samples ) ) ) ) ) ) ) ) ) . )
(ROOT (S (VP (VB Have) (NP (NP (NN difficulty)) (PP (IN in) (S (VP (VBG describing) (NP (NP (DT the) (NNS properties)) (PP (IN of) (NP (NNS minerals) (CC and) (NN rock) (NNS samples))))))))) (. .)))
Have difficulty in describing the properties of minerals and rock samples.
(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))))))))) (. .)))