( Color ( ( ( ( is not ) always ) ( ( the ( best way ) ) ( to ( ( ( identify minerals ) but ) ( is ( ( a ( useful category ) ) ( for students ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Color)) (VP (VBZ is) (RB not) (ADVP (RB always)) (SBAR (S (NP (DT the) (JJS best) (NN way)) (VP (TO to) (VP (VP (VB identify) (NP (NNS minerals))) (CC but) (VP (VBZ is) (NP (NP (DT a) (JJ useful) (NN category)) (PP (IN for) (NP (NNS students)))))))))) (. .)))
Color is not always the best way to identify minerals but is a useful category for students.
(ROOT (S (SBAR (IN Although) (S (NP (PRP it)) (VP (VBZ is) (NP (DT the) (JJS easiest) (S (VP (TO to) (VP (VB observe)))))))) (, ,) (NP (NN color)) (VP (VBZ is) (RB not) (ADJP (JJ ideal) (PP (IN as) (NP (DT a) (JJ sole) (NN way)))) (S (VP (TO to) (VP (VB identify) (NP (NNS minerals)))))) (. .)))