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Minerals, rocks, discontinuities and rock mass
Published in Ömer Aydan, Rock Mechanics and Rock Engineering, 2019
Syenite is coarse-grained intrusive igneous rock of the same general composition as granite. However, the quartz is either absent or present in relatively small amounts (less than 5%). The name of this rock is related to syenites in the Syene region of Egypt.
Magmatism and Magmatic Rocks
Published in Aurèle Parriaux, Geology, 2018
The first minerals to form are olivine and anorthite. The remaining liquid reacts with these minerals to form amphibole and a slightly more sodic plagioclase. The reaction stops here as a result of the complete consumption of the magma (Fig. 6.14). The composition of amphibole and intermediate plagioclase with less than 50% calcium is typical of diorites. When the calcium and sodium concentrations are less than potassium, this kind of magma will form a rock called syenite in which potassium feldspar predominates.
Industrial Minerals
Published in Earle A. Ripley, E. Robert Redmann, Adèle A. Crowder, Tara C. Ariano, Catherine A. Corrigan, Robert J. Farmer, L. Moira Jackson, Environmental Effects of Mining, 2018
A. Ripley Earle, Robert E. Redmann, Adèle A. Crowder, Tara C. Ariano, Catherine A. Corrigan, Robert J. Farmer, Earle A. Ripley, E. Robert Redmann, Adèle A. Crowder, Tara C. Ariano, Catherine A. Corrigan, Robert J. Farmer, L. Moira Jackson
Nepheline syenite is used in the manufacture of glass, in ceramic glazes, in tiles, and as a filler in paints and plastics. Production of nepheline syenite rose from 200 kt in 1958 to 600 kt in 1974. Output remained constant at this level until 1980, at which time it dropped significantly. This drop is attributed to the recycling of waste glass.
Genetic and ore-forming ages of the Fe–P–(Ti) oxide deposits associated with mafic–ultramafic–carbonatite complexes in the Kuluketage block, NW China
Published in Australian Journal of Earth Sciences, 2019
W. Chen, X. B. Lü, X. F. Cao, Q. Yuan, X. D. Wang
The pyroxenite, which makes up about 85% of the outcrop area, is grey to grey-green in colour and consists of diopside (75–95 vol%), with minor biotite, hornblende, olivine, magnetite, and apatite (Figure 4a, d, e). The hornblendite, which accounts for about 5% of the outcrop area, occurs in the southeastern portion of the complex. This hornblendite is grey-green in colour and consists of 80 vol% hornblende, with minor pyroxene, biotite, magnetite, and apatite (Figure 4b, f, j). The gabbro, which accounts for about 5% of the outcrop area and occurs in the eastern portion of the complex, is grey to grey-green in colour and consists of 30–40 vol% pyroxene, 40–50 vol% plagioclase and minor biotite, and augite (Figure 4g). The syenite, which accounts for about 4% of the outcrop area in the southeastern portion of the complex, is grey-pink in colour, and it is made up of plagioclase, K-feldspar, and minor biotite (Figure 4c, j). Biotite granite and quartz syenite mainly occur in the southeastern portion of the complex and account for about 1% of the outcrop area. The biotite granite phase is grey-pink and dark pink in colour, and it mainly consists of plagioclase, K-feldspar, quartz, biotite, and hornblende (Figure 4h). The quartz syenite phase is grey-pink in colour, and it is composed of plagioclase, K-feldspar, quartz, and minor biotite (Figure 4i).
Character and tectonic setting of plutonic rocks in the Gällivare area, northern Norrbotten, Sweden
Published in GFF, 2019
Zmar Sarlus, Olof Martinsson, Tobias E. Bauer, Christina Wanhainen, Joel B. H. Andersson, Roger Nordin
Syenite occurs as small bodies within the western part of the Vassaravaara complex, as well as in the Bergmästergruvan and Sikträsk (Fig. 5C, D; sample nos. 4, 29, 32 and 33 in Fig. 1). The syenite bodies have equigranular texture, are moderately foliated and characterized by a light pink color. The mineral composition comprises K-feldspar (65%), mainly microcline, plagioclase (15%), biotite (10%), amphibole (5%), quartz (5%), minor chlorite, and accessory titanite, zircon, apatite, rutile and magnetite. Amphibole and biotite grains define the foliation planes. Within the Sikträsk sample, the amphibole is strongly altered to an assemblage of chlorite, titanite and opaque phases, mainly magnetite (Fig. 5E). Secondary titanite also rims the opaque iron oxides. Quartz exhibits undulatory extinction and plagioclase is weakly sericitized. Microcline is perthitic. Partial recrystallization of plagioclase and microcline grains is common.
Relationships between magmatism and deformation in northern Yorke Peninsula and southeastern Proterozoic Australia
Published in Australian Journal of Earth Sciences, 2018
A. Brotodewo, C. J. Tiddy, A. Reid, C. Wade, C. Conor
The syenite comprises K-feldspar, quartz, biotite, magnetite, plagioclase and minor amphibole. Microcline and microperthite feldspars are evident within this phase. Evidence of sericite alteration is also seen along with hematite staining. Biotite is euhedral and along with K-feldspar is aligned within the dominant foliation preserved in the granite. Localised brecciation shows a stockwork of hematite veining that is predominantly developed around altered feldspars and within quartz grains (Figure 5b).