Mineral assemblages in phonolite occurrences are usually abundant feldspathoids ( nepheline, sodalite, hauyne, leucite and analcite ) and alkali feldspar ( sanidine, anorthoclase or orthoclase ), and rare sodic plagioclase.
32.
Phonolite lavas formed in the East African rift in particularly large quantity, and the volume there may exceed the volume of all other phonolite occurrences combined, as discussed by Barker ( 1983 ).
33.
Phonolite lavas formed in the East African rift in particularly large quantity, and the volume there may exceed the volume of all other phonolite occurrences combined, as discussed by Barker ( 1983 ).
34.
The name phonolite comes from the Ancient Greek meaning " sounding stone " because of the metallic sound it produces if an unfractured plate is hit; hence the English name " clinkstone ".
35.
The typical range of phenocrysts in ignimbrites are biotite, quartz, sanidine or other alkali feldspar, occasionally hornblende, rarely pyroxene and in the case of phonolite tuffs, the feldspathoid minerals such as nepheline and leucite.
36.
Erected between 1260 1280 on the phonolite hill of Velk?Bezdz, above sea level, it became the characteristic dominant feature of the local landscape and met the demands for an inaccessible as well as respectable royal castle.
37.
The rock would have had to cool very slowly so as to form the slender pencil-shaped columns of phonolite Big Bend Ranch State Park, at the southwesternmost visible extent of the Ouachita orogeny, lies the Solitario.
38.
It occurs interbedded with oil shales or marls ( Green River Formation, US ) and in boron-bearing evaporite deposits ( California, US ); rarely in vugs in phonolite ( Point of Rocks, New Mexico ).
39.
The 500-sq-meter ( 600-sq-yd ) single-storey, three-wing building made of phonolite blocks quarried just outside Nairobi is the only remaining corner of what was to have been a square of public buildings.
40.
It is characteristic of the later volcanic rocks rich in alkalis, such as phonolite, nepheline-basalt, leucite basalt, etc ., and also of certain plutonic rocks of the nepheline syenite series, which are typically developed in southern Norway.
