Sturtian glacial sediments south of Yunta contain haematitic and magnetitic siltstones (banded iron formation) and haematitic and magnetitic tillites formed by chemical deposition of magnetite euhedra in a finer grained haematite groundmass. Both types of bed contain clastic impurities. These rocks form part of the Braemar Iron Formation, which occurs as a discrete horizon over a length of more than 70 miles in various parts of the Olary Province. The major known deposit is at Razorback Ridge, where beds dipping 30 to 40 degrees aggregate up to 500 feet in thickness over a strike length of up to 12,000 feet. From results of drilling, mapping, exploratory mining and bulk sampling carried out to date, this deposit is believed to contain at least 200 million tons of ore averaging 25.5% Fe. A number of metallurgical investigations are currently underway to determine the best method of processing the ore, and progress to date is noted.