( ( Reference materials ) ( ( were ( prepared ( by ( mixing ( powders ( of ( ( ( ( ( natural minerals ) ( plagioclase ( , ( ( quartz and ) hornblende ) ) ) ) , ) and ) ( natural ( aphyric ( rhyolitic glass ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Reference) (NNS materials)) (VP (VBD were) (VP (VBN prepared) (PP (IN by) (S (VP (VBG mixing) (NP (NP (NNS powders)) (PP (IN of) (NP (NP (JJ natural) (NNS minerals)) (ADJP (JJ plagioclase) (, ,) (JJ quartz) (CC and) (JJ hornblende)) (, ,) (CC and) (NP (JJ natural) (JJ aphyric) (JJ rhyolitic) (NN glass)))))))))) (. .)))
Reference materials were prepared by mixing powders of natural minerals plagioclase, quartz and hornblende, and natural aphyric rhyolitic glass.
(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))))))) (. .)))