Feldspathoid

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Related to feldspathoidal: alkali feldspar, sanidine

feldspathoid

[′fel‚spa‚thȯid]
(geology)
Aluminosilicates of sodium, potassium, or calcium that are similar in composition to feldspars but contain less silica than the corresponding feldspar.

Feldspathoid

 

a group of alkali rock-forming minerals (aluminosilicates) that are not as rich in silica as the feldspars. The structure of the feldspathoids characteristically includes additional anions, such as Cl, CO32–, SO42–, S2–, and sometimes H2O. The feldspathoids replace the feldspars in alkalic rocks and some basic rocks. The major feldspathoid minerals include nepheline, leucite, sodalite, nosean, haiiyne, and cancrinite.

References in periodicals archive ?
Baloch, "The Koga feldspathoidal syenite, northwestern Pakistan: mineralogy and industrial applications", Ph.
Hibsch (1915) recognized at least two petro-graphically different sets of lavas in the Dobranka area: (i) the lower set of nepheline to sodalite "teph-rites" with a tendency towards feldspathoidal trachyandesite (e.
The studied feldspathoidal trachyandesite lava flow was exposed by erosion in the valley of the Dobrnsky potok Creek, particularly in its right bank, NE of Bfeziny (altitude of 270-280 m a.
Two new bulk chemical analyses of feldspathoidal trachyandesite from Dobranka are presented in Table 6 (fresh sample DO-1-1 and zeolitized sample DO-1-2) including trace element analyses (Table 7).
The feldspathoidal trachyandesite is characterized by lower contents of compatible elements (in ppm), such as Ni (5-6), Cr (8.
The sum of REE in the feldspathoidal trachy-andesite (381-389 ppm) is lower than that in other rocks of the Decin Fm.
Zeolites, the origin of which was accompanied by low-temperature auto-hydrothermal alteration of feldspathoidal trachyandesite lava flow, are mainly developed in amygdales.