Iron ore exploration looks for bodies of iron-rich rock large enough, rich enough and close enough to transport to supply steel mills for decades. Most of the world’s supply comes from high-grade hematite formed in banded iron formations, plus magnetite ores that are upgraded before sale. The same logic of tonnage, grade, impurities and logistics carries over to bauxite, phosphate and potash, which this guide covers alongside.

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Figures come from the US Geological Survey’s Mineral Commodity Summaries 2026 unless stated otherwise. The USGS publishes a new edition every February, so check the latest one before quoting a production or reserve number. For the prospecting principles shared across our deposit guides, see our mining prospecting guide to deposit types and field signs.

“Morocco holds about 50 billion of the world’s 73 billion tonnes of phosphate rock reserves.”

Iron ore exploration: what the target looks like

Iron ore comes in two main commercial forms. High-grade hematite ores are shipped with little processing. Lower-grade magnetite ores, such as the taconites of the Lake Superior district, need crushing, magnetic separation and pelletising before sale. The USGS notes that US resources are mainly those low-grade taconite ores, which require beneficiation and agglomeration.

Banded iron formations (BIF) are the source rock for most of the world’s supply. A University of Johannesburg study by Smith and Beukes notes that BIF-hosted high-grade hematite deposits, above 60% iron, make up the bulk of world iron ore production and reserves. They formed mainly by supergene or hydrothermal leaching of silica from the iron formation, which concentrated the iron that was left behind.

Methods that find iron ore

Iron ore exploration is unusually friendly to geophysics. Magnetite is the most magnetic common mineral, so aeromagnetic surveys map magnetite-rich units directly, and hematite bodies are dense enough to show on gravity. Geoscience Australia’s magnetics data, flown mostly at 400 m line spacing or closer since 1990, is a standard starting point in Australia. Satellite imagery then maps iron oxide at surface, outcrop and the ridges that BIF often forms.

Iron ore exploration step by step

1. Regional targeting. Government geological maps and aeromagnetics outline iron formations and magnetite-rich units; satellite imagery shows iron-oxide surfaces and the ridges that iron formation often holds up.
2. Mapping and rock-chip sampling. Walk the ridges, map where the iron formation has been enriched, and sample for Fe and impurities.
3. Ground gravity and magnetics. Gravity outlines dense hematite bodies; detailed magnetics maps magnetite and the folds and faults that thicken ore.
4. RC drilling on a grid. Reverse-circulation holes give samples for grade and impurities quickly; diamond holes add density, structure and metallurgy.
5. Metallurgical and product testing. Lump-to-fines ratio for hematite; grind size, magnetic separation recovery and concentrate grade for magnetite.

Iron ore exploration moves faster than most metal exploration because the targets are large and the geophysics responds directly to the ore. The slow part is everything after: proving tonnage to a high confidence, testing the product with steel mills, and securing rail and port capacity. Many iron ore exploration projects with good geology stall at that stage.

Iron ore exploration in Australia, Brazil and Canada

Australia dominates. The USGS lists Australian crude-ore reserves of about 59 billion tonnes, containing about 27 billion tonnes of iron, and usable-ore production of about 980 million tonnes in 2025. Brazil holds about 34 billion tonnes of crude ore and Russia about 35 billion. Canada produced about 69 Mt and reported crude-ore reserves of about 6 billion tonnes. In West Africa, Mauritania produced about 15 Mt from reserves of about 10 billion tonnes of crude ore.

World resources, by the USGS estimate, exceed 900 billion tonnes of iron ore containing more than 260 billion tonnes of iron. The shortage is never iron itself. It is high-grade, low-impurity ore close to a port, which is exactly what iron ore exploration programmes in these countries compete to find.

Iron ore exploration in practice: grade, impurities and the benchmark

Iron ore is priced against a benchmark. The USGS reports the unit value for imported 62% iron fines, CIF Tianjin port in China, averaged US$99.07 per tonne in the first nine months of 2025, down from US$112.07 in the same period of 2024. Ore above 62% Fe usually earns a premium; ore below it, or with high silica, alumina or phosphorus, usually earns a discount.

That is why iron ore exploration reports iron grade alongside the main impurities from the first drill hole. A deposit at 58% Fe with low alumina may sell better than one at 61% with high phosphorus. It is also why drill spacing and density measurements matter: a small error in density across hundreds of millions of tonnes changes the resource by tens of millions.

South Africa iron ore

South Africa produced about 66 million tonnes of usable iron ore in 2025, according to the USGS iron ore summary, with crude-ore reserves of about 1,200 Mt. Smith and Beukes describe the largest deposits as hosted by iron formation on the Maremane Dome between Sishen and Postmasburg in the Northern Cape, supplying about 78 Mt a year of high-grade hematite ore at the time of their study. For explorers, the lesson is that high-grade hematite sits where the iron formation has been leached and structurally thickened, so mapping structure around known BIF belts is the core of South African iron ore exploration. Licensing is covered in our South Africa mining licence guide.

Tanzania iron ore

Tanzania’s best-known iron ore is titaniferous magnetite rather than hematite. The Tanzania High Commission’s minerals outlook describes titaniferous magnetite bodies associated with anorthositic gabbro at Liganga in the southwest, about 80 km from the Ketewaka-Mchuchuma coal resources, and further occurrences at Maganga Hills, Lugarawa and Mlangali in Ludewa District and at Kisaki in Morogoro District. These ores carry iron oxide, vanadium pentoxide and titanium dioxide, which makes magnetic surveys the obvious first tool and metallurgy the main risk.

Bauxite exploration: weathering profiles and plateaus

Bauxite is the only commercial raw material for alumina, according to the USGS bauxite and alumina summary. It forms by intense tropical weathering of aluminium-rich rocks, which strips out silica and leaves aluminium hydroxides in a laterite profile. Deposits are typically flat-lying blankets on plateaus and old erosion surfaces, often only a few metres to tens of metres thick.

That shape drives the method. Bauxite exploration maps plateaus and laterite caps from satellite imagery and elevation data, then drills on a regular grid to measure the thickness of the bauxite layer, the overburden above it and the grade. The key grade numbers are available alumina and reactive silica, because reactive silica consumes caustic soda in the Bayer refining process. The USGS estimates that 63% of the bauxite consumed in the United States in 2025 was refined by that process.

• Resources: the USGS estimates world bauxite resources at 55 to 75 billion tonnes, 32% of them in Africa, 23% in Oceania and 21% in South America and the Caribbean.
• Reserves: Guinea about 7.4 billion tonnes, Australia 3.7 billion, Vietnam 3.1 billion and Indonesia 2.9 billion.
• Policy risk: in August 2025 Guinea revoked bauxite licences held by a subsidiary of a UAE-based aluminium producer and reallocated them to a state-backed company, the USGS reports.

What a bauxite exploration drill programme measures

Bauxite drilling is shallow and repetitive, which makes discipline the main quality control. Each hole logs the overburden, the bauxite layer and the clay or saprolite below, and samples the bauxite in short intervals. Laboratories then report total and available alumina, reactive and total silica, iron and moisture. Bulk density is measured separately, because tonnage depends on it as much as on area and thickness. A good programme also records the plateau boundary on every drill line, so the resource model stops where the blanket really stops.

Bauxite deposits in Ghana

Ghana’s bauxite is concentrated in three areas: Awaso, Nyinahin and Kyebi. Ghana’s state aluminium corporation, GIADEC, put total national bauxite at about 920 million tonnes in June 2025, as reported by Citi Newsroom, after six mining leases were approved for it. A GIADEC resource estimate at Nyinahin Block B found at least 375 million tonnes on three hills, against a historical estimate of 250 million, as Graphic Online reported. For private explorers, Ghana’s licensing rules are in our Minerals Commission licence guide.

Phosphate exploration: sedimentary basins and igneous complexes

Phosphate rock comes from two very different settings. The USGS phosphate rock summary says most resources are sedimentary marine phosphorites, with the largest deposits in northern Africa, the Middle East, China and the United States. Significant igneous deposits occur in Brazil, Canada, Finland, Russia and South Africa. World resources exceed 300 billion tonnes, and the USGS states there are no imminent shortages.

How phosphate is explored

• Sedimentary phosphorites: basin stratigraphy first. Beds follow particular marine horizons, so mapping and drilling along the favourable layer is the core of phosphate exploration. Radiometric surveys can help, because phosphorites often carry uranium.
• Igneous (carbonatite and alkaline) deposits: circular intrusions that show clearly on magnetics and radiometrics, explored by drilling the weathered cap and fresh rock.
• Grade: reported as % P2O5, with impurities such as magnesium, iron, aluminium and cadmium that affect processing and fertilizer quality.

Phosphate exploration results only mean something alongside a beneficiation test. Raw phosphate rock is usually washed, screened or floated to raise its P2O5 grade and remove clay and carbonate before it can be sold or turned into phosphoric acid. The USGS notes that Florida producers have faced lower P2O5 content as reserves decline, one reason US production has held at about 20 million tonnes a year while imports rose. A deposit’s saleable grade after upgrading, not its in-situ grade, sets its value.

Production is concentrated. China mined about 110 million tonnes of marketable phosphate rock in 2025, Morocco 36 million, the United States 20 million and Russia 14 million. The USGS lists significant new projects planned after 2028 in Canada, Congo (Brazzaville), Guinea-Bissau and Senegal. In East Africa, the Tanzanian High Commission outlook mentions phosphate exploration projects at Sengeri in Mbeya and in the Bahi Basin in Dodoma, where mapping was complete but drilling tests were still needed.

Potash exploration: deep evaporite basins

Potash exploration is the deepest of the four. The USGS potash summary describes US resources of about 7 billion tonnes, most of them at depths of 1,800 to 3,100 metres in Montana and North Dakota, as an extension of the Williston Basin deposits in Manitoba and Saskatchewan. The Paradox Basin in Utah holds about 2 billion tonnes, mostly deeper than 1,200 m, and a resource under central Michigan lies at about 2,100 m.

At those depths, surface methods do little. Potash exploration relies on oil and gas well logs, seismic reflection data and deep core holes to map evaporite beds, their thickness and their grade in % K2O. Old petroleum wells are often the cheapest dataset a potash explorer can buy. Canada led world production at about 15 million tonnes of K2O in 2025, followed by Russia at 10 million, China at 6.3 million and Belarus at 6 million.

New mines are coming. The USGS reports world potash capacity of 66.1 million tonnes K2O in 2025, projected to reach 77.4 million by 2029, with new muriate of potash mines planned in Belarus, Brazil, Canada, Ethiopia, Morocco and Spain after 2029. A Michigan project received a conditional US$1.26 billion loan commitment from the US Department of Energy in January 2025. Both potash and phosphate rock were added to the final 2025 US List of Critical Minerals.

Where potash exploration goes wrong

Deep evaporite beds are rarely flat and uniform. Salt can dissolve, flow or be replaced by barren rock, leaving gaps that seismic may not resolve. Water-bearing layers above the salt are the other major risk, because flooding can end an underground potash mine. That is why potash explorers drill more core than their surface area alone would suggest, and why the hydrogeology study matters as much as the grade.

Mineral sands exploration and how the four compare

Mineral sands are beach and dune deposits of heavy minerals: ilmenite, rutile, zircon and monazite. The USGS titanium mineral concentrates summary puts ilmenite at about 90% of world titanium mineral use. China, Mozambique and South Africa were the leading producers of titanium mineral concentrates in 2025, and Australia produced about 200,000 tonnes of rutile (TiO2 content). Kenya produced 41,000 tonnes of rutile in 2024 and none in 2025. Mineral sands exploration maps old shorelines and dunes from imagery and elevation data, then drills with aircore or auger to measure heavy-mineral content.

Where satellite screening fits bulk-mineral exploration

Bulk deposits are large and often shallow, which suits remote sensing. Imagery and elevation data map BIF ridges, laterite plateaus, old shorelines and drainage; spectral bands map iron oxides at surface. Our satellite-based mineral detection analyses multispectral and hyperspectral data over your boundary to flag target zones, alteration, faults and fractures. Iron is on our published list of detectable materials, along with industrial minerals such as gypsum, dolomite and quartz. For bauxite, phosphate or potash targets, ask us through the mining query form what a structural and surface screen can add for those.

• Input: coordinates, KML/KMZ or a polygon, plus country and target mineral.
• Output: high-potential zones, prospectivity heatmaps, estimated location and depth ranges, geological interpretation, PDF and GIS files.
• Time and cost: 5–20 business days; timelines cut from months to days and early-exploration costs lowered by up to 80–85%.
• Premium+: TargetMax™ drilling-angle recommendations and 3D subsurface models.

We have scanned 100,000+ hectares for 20+ mineral types across 25+ countries. Draw your licence on mining.farmonaut.com (Map Your Mining Site) to start, or see a sample of satellite-driven 3D mineral prospectivity mapping.

Frequently asked questions

Reviewed September 2026 against the USGS Mineral Commodity Summaries 2026 chapters on iron ore, bauxite and alumina, phosphate rock, potash and titanium mineral concentrates, Smith and Beukes (2016) on South African BIF-hosted hematite, the Tanzania High Commission’s minerals outlook, GIADEC’s bauxite statements reported by Citi Newsroom and Graphic Online, and Geoscience Australia’s magnetics page.

Production, price, reserve and capacity figures are estimates that the USGS revises every February; check the latest edition. The calculator is a pro-rata screen that ignores real premiums, penalties and costs. Nothing here is investment advice. Satellite targets are exploration targets, not mineral resources, and need drilling to confirm.