About this trail:
Lujavrite is a nepheline syenite. It is a greyishgreen to black, middle to coarse grained intrusive rock. It occurs in alkaline intrusions. The main constituents are amphibole, aegirine nepheline and feldspar. Lujavrite has a trachytoide structure.
Trail link: http://trailfire.com/cereal/trails/36213
Summary: http://trailfire.com/cereal/trailview/36213
Summary: http://trailfire.com/cereal/trailview/36213
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Lujavrite is a nepheline syenite. It is a greyishgreen to black, middle to coarse grained intrusive rock. It occurs in alkaline intrusions. The main constituents are amphibole, aegirine nepheline and feldspar. Lujavrite has a trachytoide structure.
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Marble is a well known metamorphic rock. It is formed by metamorphose of limestone and it consists mainly of intergrown Calcite crystals. It is used for ornamental purposes. Most famous marble quarries in Russia are near Sludyanka at the southern tip of Lake Baikal.
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Nephelinesyenite is a so called foid-syenite. It can be regarded as silica poor syenite, where because of lack of silica, feldspars are (partially) replaced the foid mineral nepheline. Nephelinesyenite consists of nepheline with a variable amount of feldspar (albite, orthoclase or microcline).
