( ( For example ) ( , ( quartz ( ( is ( ( a mineral ) ( as ( is copper ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN For) (NP (NN example))) (, ,) (NP (NN quartz)) (VP (VBZ is) (NP (NP (DT a) (NN mineral)) (SBAR (IN as) (S (VP (VBZ is) (NP (NN copper))))))) (. .)))
For example, quartz is a mineral as is copper.
(ROOT (S (NP (DT The) (NN mineral) (NN quartz)) (VP (VBZ is) (VP (VBN used) (S (VP (TO to) (VP (VB produce) (NP (NN glass))))))) (. .)))