-
Other common accessory minerals are apatite, titanite,
zircon and
other opaques. Most
syenites are
either peralkaline with high
proportions of alkali...
- granite,
zircon is rare and, if present, it is as xenocrysts. On the
other hand,
nepheline syenite gneiss contains abundant and
large zircon crystals...
- (pyrochlore), (corundum), (sodalite).
Syenite and quartz-
syenites:
Alkaline pegmatites: albite, nepheline, pyroxene, magnetite,
zircon, (pyrochlore), (mo****te),...
- they
occur as ****s or as thin sills,
often in ****ociation with
nepheline syenite; and they seem to bear a
complementary relationship to
certain types of...
-
deposits in the
United States—anorthosite, clay, laterite, and
nephelite syenite (to the
extent that
alumina and
aluminum compounds are
extracted from it)...
- (6.6Â ft) thick. In some rare
cases nodules are
filled with
zircon. To the west the
syenite porphyry borders the
Kurravaara conglomerate which underlies...
- An
agpaitic rock is a
peralkaline igneous rock,
typically nepheline syenite or phonolite.
Characteristic minerals in
these rocks include complex silicates...
- Some of
these terrestrial rocks are carbonatite, kimberlite,
alkaline syenite, some
rocks of
layered mafic intrusions,
diabase ****s,
gabbroid sills...
-
forming (1) gabbro, diorite,
tonalite and
granite or (2) gabbro, diorite,
syenite and granite. If
magma resides in a
chamber for a long period, then it can...
-
sequence of
metamorphic facies and
formed around 1.9
billion years ago.
Zircon grains in
these rocks match those in Labrador,
Greenland and Scotland, indicating...
