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biotite

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biotite

biotite Sentence Examples

  • The principal members of the group are muscovite, biotite, phlogopite and lepidolite.

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  • 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.

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  • 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).

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  • Calc-schists are usually argillaceous limestones in which a large development of biotite or phlogopite has occasioned foliation.

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  • 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).

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  • Biotite >>

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  • The granite (biotite, biotite-muscovite and quartz-monzonite) is of fine quality, and has been used extensively in the United States for building and monumental purposes; and the burning of lime is by far the most important industry of the city.

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  • Few obsidians are entirely vitreous; usually they have small crystals of felspar, quartz, biotite or iron oxides, and when these are numerous the rock is called a porphyritic obsidian (or hyalo-liparite).

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  • The best developed crystals are those of Vesuvian biotite.

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  • The angle between the optic axes varies from 70 0 -50° in muscovite and lepidolite to Io - o° in biotite and phlogopite; the latter are thus frequently practically uniaxial.

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  • (K,Li)3[Al(OH,F)2]FeAl2S15016 Biotite.

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  • Muscovite and biotite are commonly found in siliceous rocks, whilst phlogopite is characteristic of calcareous rocks.

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  • The best crystallized specimens of any mica are afforded by the small brilliant crystals of biotite, which encrust cavities in the limestone blocks ejected from Monte Somma, Vesuvius.

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  • Other minerals which occur in the rocks of this group are calcite, garnet, biotite, chloritoid, epidote, tourmaline and graphite or dark carbonaceous materials.

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  • The Conway quarries, four in number in 1908, are on either side of the Saco river, south-east and south-west of North Conway; their output is coarse constructional stones, all biotite or biotite-hornblende, but varying in colour, pinkish (" red ") and dark-yellow greenish-grey (" green ") varieties being found remarkably near each other at Redstone, on the east side of the Saco valley.

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  • Biotite and olivine are not really frequent in these rocks, and usually have been affected by resorption.

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  • The township is the centre of the granite industry of the state; the quarries are near the villages of Westerly and Niantic. The granite is of three kinds: white statuary granite, a quartz monzonite, with a fine even-grained texture, used extensively for monuments; blue granite, also a quartz monzonite and also much used for monuments; and red granite, a biotite granite, reddish grey in colour and rather coarse in texture, used for buildings.'

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  • Milford granite is the typical stone of an area reaching into Rhode Island south of the southern boundary of Providence county; it is a biotite granite of post-Cambrian age, is generally pinkish-gray in colour (owing to the large proportion of feldspar among its constituents), and is widely used for building purposes.

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  • The gneiss is mostly grey, but occasionally pinkish, its essential constituents (felspar and quartz) being almost always associated with dark mica (biotite) and hornblende in variable quantity.

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  • Chlorite arises from biotite, augite and hornblende.

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  • The use of a prepared rock slide containing biotite to demonstrate pleochroism and to align the polariser east-west is also described.

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  • biotite mica.

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  • biotite crystals.

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  • Here biotite + sillimanite + quartz aggregates occupy embayments in a neosome garnet.

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  • feldspar minerals with smaller amounts of dark hornblende and biotite.

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  • The darker bands, between 5mm and 10mm thick, are rich in biotite mica.

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  • The angle between the optic axes varies from 70 0 -50° in muscovite and lepidolite to Io - o° in biotite and phlogopite; the latter are thus frequently practically uniaxial.

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  • To the first class, with the optic axial plane perpendicular to the plane of symmetry, belong muscovite, lepidolite, paragonite, and a rare variety of biotite called anomite; the second class includes zinnwaldite, phlogopite, lepidomelane and most biotites.

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