KROMINCO, INC
Copyright 2008 Krominco, Inc. All rights reserved.
The company's mineral property, found in the northern part of Dinagat Island, is underlain by ultramafic rocks which include highly serpentinized dunite and harzburgite that are closely associated with hypabyssal gabbro bodies (diabase). The ultramafic rocks are highly fractured and jointed because of their position within the Philippine Mobile Belt. In most of the areas covered by the expoloration, the ultramafic complex was seen to be overlain by lateritic soil, in some areas containing high grade chromite sands.
This phenomenon is attributed to the erosion of either massive chromite deposits themselves, or dunite rocks containing disseminated chromite. The secondary chromite sands were subsequently carried down, deposited and concentrated to lower levels along with the lateritic soils.
Chromite mineralization in the region occurs mainly as parallel layerings, lenses, pods and as disseminations or nodules in peridotite, formed during the different stages of gravitational settling in the ophiolite's Dunite-Harzburgite Transition Zone. The major faults in the area trend in the northest - southwest direction. They have great influence in the topography, and provide structural control over the chromite mineralization and deposition in the region.
The assemblage of mafic and ultramafic rocks in the island is seen to be in thrust contact with the underlying metamorphic basement rock unit called as Nueva Estrella Amphibolite Schist (NEAS). The rock unit is believed to be part of an oceanic lithosphere which undergone metamorphosis due to the emplacement of assemblage of mafic and ultramafic rocks in the island. Upon metamorphism these rocks were transformed into amphibolites chloride muscovite schist and quart mica schist respectively.
Four types of mineral deposits were observed in the island namely : hydrothermal gold, placer gold, orthomagmatic or primary chromite mineralization and residual / alluvial in laterite. Likewise, four chromite ore textures are observed in the island - massive, layered, disseminated and nodular ores. All textures are seen to grade into each other.
Krominco Geological Setting
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