nepheline-basalt

rock

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July 1, 2026

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Nepheline-basalt is an extrusive igneous rock characterized by a low silica content and a dark color, rich in iron and magnesium. It is a type of basalt where the mineral nepheline has replaced feldspar, either entirely or partially. Nepheline itself is a feldspathoid mineral composed of sodium and potassium aluminosilicate.12

Basalts can be broadly classified into tholeiitic and alkali basalts. Nepheline-basalts fall under the alkali basalt category. These rocks are typically fine-grained and dark-colored, with occurrences noted in Germany, the United States, Turkey, and Libya. Nepheline syenite, a related intrusive rock, also contains nepheline and feldspar but is poorer in silica and richer in alkalies than granite.13

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basalt
…the rock is known as nepheline-basalt; if the replacement is only partial, the term nepheline-basanite is used. Similarly, there are analcime- and leucite-basalts and leucite-basanites. Most nepheline-basalts are fine-grained, very dark-coloured rocks and date to the early Cenozoic Era (65.5 million years ago to the present). They are fairly common…
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…the rock is known as nepheline-basalt; if the replacement is only partial, the term nepheline-basanite is used. Similarly, there are analcime- and leucite-basalts and leucite-basanites. Most nepheline-basalts are fine-grained, very dark-coloured rocks and date to the early Cenozoic Era (65.5 million years ago to the present). They are fairly common…
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