The Ramu chromite deposit occurs
in the Marum Ophiolite complex and is
the most economically attractive chrom-
ite deposit in Papua New Guinea. Its
lateritic nickel, chromite and cobalt
potential has attracted several compan-
ies to prospect the deposit.
In the present work, the
compositions of chromite in the Ramu
lateritic deposit and coexisting
olivine-chromite pairs in Marum
Ophiolite dunite were analysed with the
electron microprobe for Fe, Mg, Cr and
Al. The results were used to determine
the relationship between the cations in
the tetrahedral and octahedral
structures of the chromite. In
addition, the Fe, Mg, Cr and Al cations
of the coexisting olivine-chromite
pairs were used to calculate the
equilibrated temperatures of
crystallisation of the chromite. The
variation of Fe", Mg and Cr cation
values of the chromite in relation to
the calculated temperatures was studied
by regression analysis.