syenite – מילון אנגלי-אנגלי
Syenite
Syenite is a coarse-grained
intrusive igneous rock with a general composition similar to that of
granite, but deficient in
quartz, which, if present at all, occurs in relatively small concentrations (<5%). Some syenites contain larger proportions of
mafic components and smaller amounts of
felsic material than most granites; those are classed as being of
intermediate composition. The volcanic equivalent of syenite is
trachyte.
syenite
nm.
syenite (Geology)
Syenite
(n.)
Orig., a rock composed of quartz, hornblende, and feldspar, anciently quarried at Syene, in Upper Egypt, and now called granite.
(n.)
A granular, crystalline, ingeous rock composed of orthoclase and hornblende, the latter often replaced or accompanied by pyroxene or mica. Syenite sometimes contains nephelite (elaeolite) or leucite, and is then called nephelite (elaeolite) syenite or leucite syenite.
Webster's Revised Unabridged Dictionary (1913), edited by Noah Porter.
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