Hollandite in Hawaiian Basalt: A Relocation Site for Weathering-Mobilized Elements

R. V. Fodor, R. S. Jacobs* and G. R. Bauer
Department of Marine, Earth, and Atmospheric Sciences, North Carolina State University, Raleigh, NC 27695 USA
Department of Land and Natural Resources, Honolulu, HI 96813, USA
*Present Address: Bass Enterprises Production, Ft. Worth, TX 76102, USA.

Abstract: Enrichments in Ba, REE and Y abundances, occurrences of REE, Y-bearing phosphate, depletions in K and Rb, and negative Ce anomalies in some lavas on Kahoolawe (Hawaii) reflect secondary mobilization of Ba, REE, Y, K and Rb. Hollandite (Ba-Mn-oxide) in the groundmass of a Kahoolawe lava contains nearly 10 wt.% BaO, ∼ 1.1 wt.% CeO2, and small amounts of La, Nd, Y, K, Na, P, Cl and Cu to provide an example of where elements mobilized during weathering processes on the Hawaiian Islands find residence. Fe-vernadite, a second Mn-oxide, also hosts mobilized REE and Ba. A positive Ce anomaly in the hollandite complements the negative Ce anomaly in some Kahoolawe lavas, this is analogous to Ce accumulation in todorokite of manganese nodules complementing Ce-depleted seawater. Mn-oxides, then, can serve as links between lavas depleted and enriched in certain elements.

Keywords: hollandite • ferruginous vernadite • trace-element mobilization • Ce anomaly • Hawaiian basalt

Mineralogical Magazine; December 1994 v. 58; no. 393; p. 589-596; DOI: 10.1180/minmag.1994.058.393.06
© 1994, The Mineralogical Society
Mineralogical Society (www.minersoc.org)