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An igneous rock composed primarily of alkali feldspar together with other minerals, such as hornblende.

[Latin Syēnītēs (lapis), (stone) of Syene, from Syēnē, Syene, an ancient city of southern Egypt, from Greek Suēnē.]

sy′e·nit′ic (-nĭt′ĭk) adj.
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7] At the cataracts of the great rivers Orinoco, Nile, and Congo, the syenitic rocks are coated by a black substance, appearing as if they had been polished with plumbago.
point load tests on fourteen rock types including Sandstone Limestone Dolomite Marble and Syenitic Gneiss to determine possible correlation between UCS and PLI and established following linear relationship:
Summary: Thorium, the radioactive metal, present in natural sediments produced in the form of detritus minerals such as monazite, rutile, granitic complexes, syenitic complexes, thorite, thorianite and progenitor of U, Th and Ac series.
In contrast the A-type syenitic and metavolcanic rocks are probably related to the compositionally similar West Barneys River plutonic suite and younger volcanic rocks formed in an extensional regime.
Madagascar geology can be divided into two major domains: (1) the upper Proterozoic crystalline basement, characterized by high-grade metamorphic rocks of igneous and sedimentary origin, and by large gabbroic to granitic and syenitic plutons representing the roots of the axial zone of the East African orogenic belt; and (2) a Permian-Mesozoic to Tertiary sedimentary sequence, formed during more or less continuous subsidence of the Mahajanga, Morondava and Toliara basins, corresponding to the paleo-Mozambique channel.
This rock is decidedly syenitic in structure, containing almost no mica, but an abundance of hornblende; resembling closely a similar rock which I found abundantly, and under like circumstances in the Island of Santo Domingo.
Paleoweathering profiles on syenitic and phonolitic bedrocks are widerspread not only in the present-day tropical and subtropical terrains (Brazil: Valeton et al.
Granosyenitic, syenitic, and quartz monzonitic rocks (mangeritic rocks after Bogatikov & Birkis, 1973) and associated gabbro-anorthosites and ultramafic rocks are found in the southern part of the batholith (Fig.
The relatively coarse grain size of xenoliths and xenocrysts indicate origin from subjacent plutonic sources, and the gabbro of Christmas Mountain and syenitic rocks of Dominguez Mountain show that such plutons exist in the Big Bend region.
Mount Kupe is a steep-sided, cone-shaped mountain of horst uplifts and syenitic and granitic intrusions formed by block faulting and bounded by structural troughs, within which volcanic activity has created small cones (Tye 1986).