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Barian-titanian biotites in nephelinites from Oahu, Hawaii

W. L. Mansker, R. C. Ewing and K. Keil
Barian-titanian biotites in nephelinites from Oahu, Hawaii
American Mineralogist (February 1979) 64 (1-2): 156-159


Late-magmatic biotites in nephelinites from Oahu, Hawaii contain unusually high amounts of BaO (up to 20 weight percent) and TiO2 (up to 14 weight percent) and are markedly low in SiO2 (21 to 28 weight percent) and K2O (2 to 6 weight percent). As BaO content increases SiO2, K2O and MgO decrease and FeO and Al2O3 increase. Atomic substitution schemes indicate that Ba substitutes entirely for K, Na and Ca in interlayer sites; Al compensates for tetrahedral Si deficiencies; and Ti is probably limited to octahedral substitution for Mg and Fe. Tetrahedral occupancy by Ti appears unlikely although undetermined Fe3+ may compensate for tetrahedral deficiencies. A substitution scheme of the type K + 3(Mg, Fe) + 3Si = Ba + 2Ti + 3Al is suggested.

ISSN: 0003-004X
EISSN: 1945-3027
Serial Title: American Mineralogist
Serial Volume: 64
Serial Issue: 1-2
Title: Barian-titanian biotites in nephelinites from Oahu, Hawaii
Affiliation: Univ. N.M., Dep. Geol., Albuquerque, N.M., United States
Pages: 156-159
Published: 197902
Text Language: English
Publisher: Mineralogical Society of America, Washington, DC, United States
References: 8
Accession Number: 1979-020859
Categories: Mineralogy
Document Type: Serial
Bibliographic Level: Analytic
Annotation: Mineral chemistry of Hawaii; Contrib. VII
Illustration Description: illus. incl. tables
N21°00'00" - N22°00'00", W158°30'00" - W157°30'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from U. S. Geological Survey, Hawaiian Volcano Observatory, , United States
Update Code: 1979
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