Sentence Examples


  • The Barre granites, like those of Woodbury and Calais (also in Washington county) and part of those of South Ryegate, Kirby and Newark (Caledonia county), are of the biotite type; they are grey, except the stone from Newark, which is pinkish.
  • In the mica-schists of this group biotite or muscovite may be the principal mineral and often both are present in varying proportions; the mica has developed from the argillaceous matter of the original rock; in addition there is always quartz and sometimes felspar (albite or oligoclase).
  • Calc-schists are usually argillaceous limestones in which a large development of biotite or phlogopite has occasioned foliation.
  • Some of the "porphyroids" which have grains of quartz and felspar in a finely schistose micaceous matrix are intermediate between porphyries and micaschists of this group. Still more numerous are orthoschists of hornblendic character (hornblende-schists) consisting of green hornblende with often felspar, quartz and sphene (also rutile, garnet, epidote or zoisite, biotite and iron oxides).
  • Under extreme crushing these basic rocks may be converted into dark biotite-schists, or greenish chloriteschists.

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