( ( Streak Streak ) ( ( refers ( to ( ( the colour ) ( of ( ( the powder ) ( produced ( when ( ( a mineral ) ( is ( rubbed ( over ( ( the surface ) ( of ( ( a piece ) ( of ( unglazed ( , ( white porcelain ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Streak) (NNP Streak)) (VP (VBZ refers) (PP (TO to) (NP (NP (DT the) (NN colour)) (PP (IN of) (NP (NP (DT the) (NN powder)) (VP (VBN produced) (SBAR (WHADVP (WRB when)) (S (NP (DT a) (NN mineral)) (VP (VBZ is) (VP (VBN rubbed) (PP (IN over) (NP (NP (DT the) (NN surface)) (PP (IN of) (NP (NP (DT a) (NN piece)) (PP (IN of) (NP (JJ unglazed) (, ,) (JJ white) (NN porcelain))))))))))))))))) (. .)))
Streak Streak refers to the colour of the powder produced when a mineral is rubbed over the surface of a piece of unglazed, white porcelain.
(ROOT (S (NP (NP (DT The) (NN color)) (PP (IN of) (NP (NP (DT the) (NN powder)) (PP (IN of) (NP (DT a) (NN mineral)))))) (VP (VBZ is) (VP (VBN called) (NP (NN streak)))) (. .)))