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Subject Domain (in DDC) Computer science, information & general works ♦ Data processing & computer science
Subject Keyword New Caledonia ♦ Nickeliferous End-members ♦ Plant Root ♦ Cryptocrystalline Aggregate ♦ Weathered Ultramafic Rock ♦ Crystallographic Data ♦ Main Cobalt Bearer ♦ Todorokite Contain ♦ Structural Model ♦ Follow-ing Mineral ♦ Intermediare Phase ♦ Continuous Ser-ies ♦ Variable Composition ♦ Cobalt Mineralization Present ♦ New Phase
Abstract A study of cobalt mineralization present in weathered ultramafic rocks from New Caledonia revealed the follow-ing minerals: heterogenite (2H and 3R polytypes), asbo-lan (with cobalt and nickel), lithiophorite, intermediare phases between asbolan and lithiophorite, cryptomelane, ramsdellite and todorokite; only lithiophorite and cryptome-lane had previously been characterized in New Caledonia. Cryptomelane, ramsdellite and todorokite contain only traces of cobalt. The other minerals, the main cobalt bearers, occur not only as cryptocrystalline aggregates but also as crystals or fibers up to several hundred pm long. They form concretions, but more often occur as pseudo-morphs after silicates and plant roots, which are habits not previously documented for these minerals. Microprobe ana-lyses show that (l) the heterogenite is much more nickelifer-ous (up to 7.5t/0 NiO) and the lithiophorite, more cobal-tiferous (up to I 1.5q0 Co2O3), than those found elsewhere;(2) the asbolan shows more variable compositions than those described elsewhere, rangrng from purely cobaltifer-ous to purely nickeliferous end-members; and (3) new phases exist with compositions between those of asbolan and lithiophorite. Thermal, chemical and crystallographic data suggest structural models that differ from those in the literature, and allow for the existence of continuous ser-ies, between cobaltiferous and nickeliferous end-members of asbolan and between asbolan and lithiophorite.
Educational Role Student ♦ Teacher
Age Range above 22 year
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Education Level UG and PG ♦ Career/Technical Study