Furthermore, high Cr and Ni contents of natural origin due to the weathering of ultramafic rock
masses, ranging from 277 to 404 mg [kg.sup.-1] and from 246 to 671 mg [kg.sup.-1], respectively, were also recorded at the coastal sediments of Evoikos Gulf .
Petrographic observations have been made for the different litho-units of the Agasthyapura deposit such as ultramafic rock
, acid intrusives and hornblendites.
The presence of allochthonous ultramafic rocks
is one of the most original characteristics of the northeastern Portugal geology (IGLESIAS & al., 1983).
Magnesite occurs as occasional small (5-20 mm) nodules and vein fragments within the strongly weathered ultramafic rock
, now largely clays, at the core of the syncline.
Tables 2 and 3 show the chemical composition in terms of the major and trace element concentrations of the ultramafic rocks
The primary unweathered ultramafic rock
is known to be the source of Pt in the overlying laterite, and for the nearby historic Fifield alluvial Pt mine.
The occurrence is found at the eastern end of a large conformable sill of altered ultramafic rock
(peridotite; Satterley, 1941), exposed as an E-W trending ridge approximately 80 m long and 10 m wide.
Preliminary geological logging has indicated there is ~1.5m of low MgO ultramafic rock
between the 1.5m and 0.5m massive sulphide zones.
The holes defined a sequence of mineralised and sheared mafics and ultramafic rock
units typical of the Cuddingwarra deposits.
The geology is a typical tropical lateritic nickel deposit containing both limonite (lower-grade) and saprolite (higher-grade) mineralised material which has been developed over ultramafic rock
Gold mineralization at Currans Find is hosted in multiple ENE-trending quartz veins within mafic and ultramafic rocks
. These rock types are also host to the Penny West and Columbia-Magenta deposits south of Currans Find.