Important that you know the geology of the area:Formation of...

Important that you know the geology of the area:

Formation of Channel Iron Deposits
During the early to mid Tertiary period (~40 Million years), the Hamersley Province and surrounding areas was covered by a blanket of iron rich lateritic material derived from the erosion of the Banded Iron Formation(BIF's) and other iron rich basement rocks. Later incision of this palaeosurface saw the development of major river valleys into which younger sediments, derived from the iron rich laterite, were later deposited. These palaeovalleys(channels)and the associated iron rich pisolitic accumulations are now referred to as Channel Iron Deposits(CID's).

CID ores differ from the classic bedded ores derived from the Brockman and Marra Mamba Iron Formations having a pisolitic texture, made up of rounded haematite ‘pea-stones’, usually less than 5mm in diameter, and rimmed with hydrated iron oxides (goethite and/or limonite) cementing the ore together. These CIDs are generally well preserved throughout the Pilbara region and are variably referred to as the Robe Pisolite (Panawonnica/Robe River), Marillana Formation (Yandicoogina) and the Poondanoo Formation (Pilbara Craton).

The CIDs are comprised of small spheroids, which were generally thought to have formed during soil formation within the iron rich lateritic surface. The spheroids developed around small haematitic nuclei, small wood fragments (charcoal) and root hairs. Subsequent accretionary layers of goethite formed the “pea-stones” seen today. Fossil wood is common within the ores accounting for up to 15% of the channel fill. Cementation of the fragments and spheroids by limonite and/or goethite occurred within the palaeochannel.

Fe grade is what is important some impurities are welcome in varying quantities.