They typically comprise early olivine and plagioclase, ophitically enclosed by augite, with opaque oxides and apatite. |
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The cpx is classified as augite based on average composition, and displays a very narrow compositional range. |
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The most common phenocryst silicate phases are olivine, plagioclase and augite, typically, although not always, appearing in that order. |
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The volcanics were described by Aghabawa as alkaline basalts, hawaiites and mugearites with plagioclase, olivine and augite as the essential constituents. |
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Thus the order of phenocryst appearance in Kilauea lavas is olivine, plagioclase, augite whereas in Mauna Loa lavas it is olivine, augite, plagioclase. |
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All basalt chemical compositions can be plotted in the basalt tetrahedron, which has normative quartz, olivine, nepheline and augite at the apices. |
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Normal alkali basalt contains olivine and, commonly, a diopsidic or titaniferous augite. |
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The diopside, jadeite, augite, protoenstatite, and spodumene structures consist of only one chain type. |
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The rock that forms the heart of Mount Royal contains large black crystals of augite, a variety of pyroxene, proof that it cooled slowly. |
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The latter form by dehydration melting at less than 10-12 kbar leaving a residue of augite, orthopyroxene, plagioclase and varying amounts of amphibole. |
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As cooling continues, plagioclase and the pyroxene mineral augite form. |
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Hedenbergite and augite are typically black. |
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Among other minerals found in them are biotite, chlorite, tourmaline, epidote, apatite, garnet, hornblende, augite, sphene and pyrites. |
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The sets of minerals of this skarn include quartz, calcite, grossular, augite, and gypsum. |
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Mafic volcanic rocks are dominantly basaltic and typically contain augite and plagioclase phenocrysts. |
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Interstitial augite and pigeonite have in part been altered to amphibole and mica. |
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They are found in alkalic rocks such as nepheline syenites and phonolites, wherein they are associated with orthoclase, feldspathoids, augite, and sodium-rich amphiboles. |
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Diallage, either of the two pyroxenes augite and diopside, which have well-developed, close-spaced, parallel partings commonly filled with magnetite or ilmenite. |
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The small clusters of coarse pyroxene and plagioclase are also found near contacts, including individual large rounded grains of augite. |
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Good crystals of augite and olivine are also to be obtained in the ash beds of Vesuvius and of many other volcanoes, ancient and modern. |
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Trachyte tuffs contain little or no quartz but much sanidine or anorthoclase and sometimes oligoclase feldspar, with occasional biotite, augite and hornblende. |
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Le Bas showed that lower magmatic Si contents in alkali basalts, when compared to tholeiites, can cause more Al to substitute for Si in augite tetrahedral sites. |
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Augite is generally complexly zoned and pleochroic and has Ti-rich rims. |
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