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Deposit Synonyms
Boo-Loo; Ceip; Central Eyre Iron Project; Dolphin; Iron Road; Ml 6467; Murphy South; Rob Roy
Mineral District
Deposit Summary
prominent, complex, arcuate EW-orientated aeromagnetic anomaly ~30km strike. Drilling identified Archean magnetite-bearing gneiss. Total mineral resource (Feb, 2015) 4.5Bt, head grade16%Fe, grind size to 106 micron for 67%Fe conc.
Deposit Description
WARRAMBOO, prominent folded arcuate ~30km EW-trending aeromagnetic complex. Drilling in the late 1950's identified a series of iron-rich beds comprising up to four main members, dipping 45 S, within an ~3300 m thick metasedimentary sequence of complexly folded, high metamorphic grade rock. Preliminary beneficiation results from diamond core for magnetite-bearing intervals indicated that for head grades of 12-15% Fe, of which 60% of the iron occurred as magnetite, grinding to pass 150 mm gave 90% recovery at 62-65% Fe (Whitten and Risely, 1968).
Iron-rich metasediment was identified as quartz-felspar-magnetite-garnet-cordierite-sillimanite gneiss (magnetite content ranging from 5 to 30% by volume), interlayered with garnet gneiss. A felsic gneiss in diamond drill hole WD 1 was dated at 2520 +-163 Ma (whole-rock Rb-Sr; Flint and Rankin, 1991). In the central north of the aeromagnetic complex a fence of RC drill holes 83 CRC 34-43 was completed in 1983 at the Pine Row prospect as follow up to a spot zinc value of 1,700ppm in an historic Mines Department drillhole. The holes penetrated a sequence of quartz-feldspar gneiss, with variable garnet to magnetite content, layered metabasics, and a micaceous ultramafic intrusive. Best value 24%Fe in hole 83 CRC 34. An unusual mafic rock possibly a lamprophyre was penetrated at the eastern end of the magnetic complex in hole 83 CRC 33.
Exploration and resource drilling with accompanying test work by Iron Road Ltd since the early 2000s has identified a major resource of low grade iron ore. Results to February 2015 were for a total resource of 4.5 Btonne @ 16%Fe for <720Mt contained iron, no overall DTR% grade provided. Measured and Indicated resources were 3.5 Btonne or 77% of total mineral resources. Total Reserves (proved = possible) = 2 Btonne at 15.5%Fe head grade.
A research paper (Lane et al, 2014), has identified an age for the iron-rich formation of ~1750Ma suggesting the presence of a much younger late Palaeoproterozoic sequence of iron-rich metasediment unconformably overlying Archean basement gneiss (2480Ma). The iron formation may equate with the magnetically anomalous Price Metasediments near Coffin Bay on the lower Eyre Peninsula, and dated at ~1790Ma.
Discovery Year
~ 1957
Commodities
Iron
Ore Minerals
Magnetite
Gangue Minerals
Biotite, Chlorite, Cordierite, Feldspar, Garnet, Quartz
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