( ( Although ( it ( is ( the ( ( hardest natural ) mineral ) ) ) ) ) ( , ( diamond ( ( has ( ( perfect cleavage ) ( in ( four directions ) ) ) ) . ) ) ) )
(ROOT (S (SBAR (IN Although) (S (NP (PRP it)) (VP (VBZ is) (NP (DT the) (ADJP (RBS hardest) (JJ natural)) (NN mineral))))) (, ,) (NP (NN diamond)) (VP (VBZ has) (NP (NP (JJ perfect) (NN cleavage)) (PP (IN in) (NP (CD four) (NNS directions))))) (. .)))
Although it is the hardest natural mineral, diamond has perfect cleavage in four directions.
(ROOT (S (NP (DT A) (JJ synthetic) (NN diamond)) (VP (VBZ is) (RB not) (VP (VBN considered) (NP (DT a) (NN mineral)) (SBAR (IN because) (S (NP (NNS minerals)) (VP (MD must) (VP (VB be) (VP (VBN created) (ADVP (RB naturally))))))))) (. .)))