Goethite vs Limonite: Differences, Iron Content and Uses

Goethite is a single mineral with a fixed formula, FeO(OH), while limonite is a field name for a mix of hydrated iron oxides that often contains goethite. So the difference between goethite and limonite is mineral versus mixture. Goethite holds 62.85% iron when pure (AusIMM). Limonite has no fixed iron figure, because its make-up changes from sample to sample.

That difference matters on real projects. A geologist who logs “limonite” is describing what the rock looks like in the field. A metallurgist who plans for “goethite” is describing a known phase with known water and iron. This guide shows how to tell them apart, how they compare with hematite and magnetite, where each one matters in exploration and processing, and how to estimate what heating will do to the grade of your own ore.

Goethite vs limonite: the main differences

The Handbook of Mineralogy lists goethite as orthorhombic α-FeO(OH), and it even notes that goethite is nearly cryptocrystalline (crystals too small to see) “in limonite”. Limonite, by contrast, is now treated as a field term for a mixture that can include goethite, lepidocrocite, akaganeite and jarosite. Its usual written formula, FeO(OH)·nH2O, is only approximate.

Goethite and limonite share a streak colour, so a streak test alone cannot separate them. It only separates this brown family from the red and black iron oxides.

Is limonite the same as goethite?

No, although the two names are often used loosely for the same brown rock. Many limonites are mostly goethite, and the USGS porphyry copper model writes “limonite (goethite, hematite, and jarosite)” to show that the word covers several minerals. X-ray work on two limonitic ores found goethite and hematite as the main crystalline phases, with goethite apparently the larger share.

The practical rule is simple. Write “limonite” in a field log when you cannot identify the phases. Write “goethite” only when a lab method supports it. Precise identification of the minerals in limonite is practical only with X-ray diffraction (XRD), a lab method that identifies crystal structures.

How to identify goethite and limonite in the field

1. Do a streak test. Rub the sample on unglazed porcelain. A yellow-brown streak points to goethite or limonite. Hematite streaks cherry-red or reddish brown and magnetite streaks black.
2. Look at the texture. Radiating needles, silky fibres or smooth botryoidal (grape-like) surfaces suggest goethite. Soft, earthy, powdery coatings suggest limonite.
3. Scratch it. Goethite at Mohs 5 to 5.5 resists a copper coin and is about as hard as glass. Powdery limonite can be much softer. Remember that a soft sample may simply be a fine-grained, porous goethite.
4. Try a magnet. Strong attraction points to magnetite in the sample. Weak or no response fits this brown group, though mixed samples can mislead.
5. Send doubtful samples to a lab. Use XRD for the phases and loss on ignition (LOI, the mass lost when a sample is heated) for the water. Ask for both when the result affects a processing decision.

Infographic

From rusty rock to a named mineral in 4 steps

1. 1StreakYellow-brown means the goethite and limonite group.
2. 2TextureNeedles or fibres suggest goethite; powder suggests limonite.
3. 3LogRecord limonite unless a lab has confirmed the phase.
4. 4LabUse XRD for phases and LOI for water.

Goethite vs hematite and magnetite: iron content compared

Goethite carries less iron than hematite or magnetite because part of its weight is water. The ideal composition is 89.86% Fe2O3 and 10.14% H2O. An S-K 1300 technical report on BHP’s Western Australia Iron Ore (2022) uses the same comparison, about 70% Fe for hematite and about 63% for goethite. If you need the wider picture, see our guide to types of ore deposits.

Chart

Iron content of pure iron minerals

% Fe by weight, ideal composition

Real ore grades sit below these ceilings because of silica, alumina and other impurities. AusIMM’s Spectrum excerpt describes martite-goethite ore (hematite after magnetite, plus goethite) as typically 60 to 63% Fe with goethite often above 50% by weight. Limonite ranks third in preference after hematite and magnetite in that same reference, and it can be worked commercially if the grade is high enough.

Density and hardness of the iron minerals

Density and hardness affect gravity separation, grinding and how the ground behaves. Goethite is lighter than hematite and magnetite. Limonite spans a wide range because porosity and composition vary. Siderite, an iron carbonate that the Handbook lists among goethite’s associated minerals, is included for comparison.

Chart

Measured density of iron minerals

g/cm³; limonite spans 2.7 to 4.3 and is not plotted

Chart

Mohs hardness range by mineral

Lowest and highest value in the cited references; limonite sources differ

Goethite formation: where it forms and why

The Handbook calls goethite a common weathering product of iron-bearing minerals in oxygen-rich settings and an important part of ore in weathered iron deposits. It also forms directly as a precipitate in hydrothermal, marine and bog settings when iron-bearing water oxidizes.

• Weathered iron formations. Supergene processes (changes driven by water moving down from the surface) replace chert and carbonate bands with iron oxides. This produces martite-goethite ore.
• Channel iron deposits. In the Pilbara of Western Australia, pisolite nodules of hematite and limonite-goethite were washed into ancient river channels. The BHP report describes goethite-hematite pelletoids in the Yandi channel.
• Gossans. Gossans are the rusty caps left when sulfide ore oxidizes near the surface. AusIMM notes that surface limonite can mark a sulfide vein below ground.
• Laterites. In nickel-cobalt laterite profiles (USGS), a limonite horizon sits above saprolite and under a ferricrete cap, typically within 26 degrees of the equator.
• Bogs and soils. Limonite occurs as bog iron ore. Goethite is found in soil and other low-temperature settings, where it adds yellow and brown colours.

Limonite and goethite uses today

These are the uses with solid evidence, ordered by their importance to mining readers.

Chart

US iron oxide pigment consumption

Apparent consumption, thousand metric tons; includes synthetic pigments; 2025 is an estimate

1. Iron ore

Goethite-bearing ore is part of the iron supply. Martite-goethite and channel iron ores are mined in the Pilbara, and USGS estimates Australia produced 980 million metric tons of usable iron ore in 2025. That figure covers all Australian ore types, not goethite alone. Our article on iron ore types compares the wider group, and direct reduction plants show where feed chemistry matters downstream.

2. Nickel and cobalt laterites

Limonite is also a term for an ore horizon in nickel laterites. Oxide-type laterite is one of three subtypes in the USGS model. It matters because USGS puts 54% of global nickel resources in laterites (2026). In this setting “limonite” names a layer in the profile, so always check how a report uses the word.

3. Ochre and iron oxide pigments

Goethite is an important part of ochre pigments. The yellow forms of limonite gave yellow ochre, and roasting partly turned it to hematite, giving red ochres and burnt tones. Modern iron oxide pigments (USGS) go into concrete, paint and coatings, ferrites, plastics and rubber. US apparent consumption was about 200,000 metric tons in 2025 (estimate), and that total includes synthetic pigments.

4. An exploration guide

The USGS porphyry model explains that the original sulfide minerals of a leached cap can be interpreted from the mineralogy, colour, texture and origin of its residual limonite. In Australian regolith work, CRC LEME researchers reported goethite as an important host for zinc, copper and arsenic in the in-situ regolith at Cobar, with hematite the main host for copper.

5. Gold in gossans

Limonite has itself been a gold ore. Gold-bearing limonite gossans were mined in Shasta County, California, at Rio Tinto in Spain and at Mount Morgan in Australia. Colour alone proves nothing, though, so assays decide.

6. Holding contaminants on mine sites

Goethite surfaces can bind metals and arsenic. A spectroscopy study on OSTI examined arsenite adsorption on goethite, hematite and other iron phases. The USGS nickel-copper sulfide model says secondary ferric hydroxides can remove metals from solution, with sorption depending on pH, and it reports goethite among the iron minerals at acidic tailings ponds and a lake surrounded by waste rock at Sudbury. This binding does not make a site safe on its own, because conditions can change, so tailings work needs site-specific test data.

7. Soil colour and soil science

Goethite is a common soil mineral and a guide to weathering. Soil colour is only a rough clue, however, and it does not replace a soil test. For mine closure work, rely on measured soil data rather than on colour.

▶ Seven environmental impacts of mining, explained in clay. · 2:31

How goethite affects processing: water, heat and grade

Heating drives off goethite’s bound water and leaves hematite. In a study of two limonitic ores, the goethite-to-hematite change occurred at 250 to 350 °C, and above 350 °C only the hematite structure was recognizable. This step is called calcining, and it matters in three ways:

• Grade rises. Removing water concentrates the iron. Pure goethite at 62.85% Fe becomes hematite at 69.94% Fe.
• Mass falls. You ship or feed fewer tonnes, but heating has a fuel cost that the grade gain has to justify.
• Reporting needs care. A grade on a calcined basis is not comparable with one on a dry basis. Check the basis before comparing two ores.

The calculator uses LOI to estimate both effects. It treats the whole LOI as water from goethite, so its goethite figure is an upper limit. Clays and carbonates also lose mass on heating, and XRD is the way to check.

Can satellites map goethite and limonite?

Satellites can flag iron-oxide-rich surfaces, but they cannot give a reliable goethite assay. A review of ASTER, ALI and Hyperion data notes that limonite, jarosite and hematite have absorption features between 0.4 and 1.1 µm, the range that remote sensing uses for iron oxides. Reference spectra are available from the USGS Spectroscopy Lab.

There are limits. One Sentinel-2 study found that iron minerals often occur as thin coatings mixed with soil, vegetation and shadow, and that broad bands reduce the ability to resolve subtle features. Treat an iron-oxide anomaly as a place to go and sample. For consultants, satellite-based mineral detection can help screen a licence before field crews deploy, and its results are exploration targets ahead of any resource estimate. Prospectivity mapping shows how layers like this are combined with other data.

▶ What a spectral signature is, and what imaging can and cannot show. · 1:49

What to check before relying on a limonite or goethite report

• Method: was the phase identified by XRD, or only by eye?
• Grade basis: is iron quoted on a dry, wet or calcined basis?
• LOI: what is it, at what temperature, and how much is due to clay?
• Word use: does “limonite” mean a mineral mixture, or a laterite horizon?
• Depth: a surface gossan or cap may not represent the rock at depth, so drill data must confirm it.
• Permission: sample only with the landowner’s permission and the right licence, and never use mercury.

For a closer look at this mineral group, see our related piece on goethite crystal, limonite and hematite. To discuss a specific project area, use the mining query form.

▶ Remote sensing for mining, explained without jargon. · 2:01

Frequently asked questions

What is the difference between goethite and limonite?

Goethite is one mineral, α-FeO(OH), with a defined crystal structure. Limonite is a field term for a mix of hydrated iron oxides, which often includes goethite.

What is goethite used for?

Mainly as part of iron ore and as a component of ochre pigments. It also helps geologists read weathered rock during exploration.

What is limonite used for?

It has been used as a low-preference iron ore, as a pigment and, where gold is present in gossans, as a gold ore. The word also names a horizon in nickel laterites.

How much iron is in goethite?

Pure goethite holds 62.85% iron by weight. Real ore is lower because of impurities such as silica and alumina.

What colour is goethite’s streak?

Brownish yellow, yellow-orange or ocher yellow. The mineral itself ranges from blackish brown to yellowish or reddish brown.

Is goethite magnetic?

A plain goethite sample usually gives little response to a hand magnet, while magnetite is strongly attracted. Treat a magnet as a quick screen, since mixed samples can mislead, and confirm with a lab.

Is goethite a hematite?

No. Hematite is Fe2O3 with no bound water and a red streak. Goethite turns into hematite when heated, losing its water in the process.

How hard is goethite?

Mohs 5 to 5.5. Its fibres are remarkable at very small scale: limpet teeth reinforced with goethite nanofibres reached 3.0 to 6.5 GPa in tensile tests, the highest then recorded for a biological material (2015).

Why is it called goethite?

It honours the German writer Johann Wolfgang von Goethe. Limonite takes its name from Greek words for a wet meadow or marshy lake, a nod to bog iron ore.

Does limonite mean there is gold nearby?

Not by itself. Limonite can mark oxidized sulfides, and some gossans carry gold, but iron staining is not proof of value. Only sampling and assays can show what is there.

More from Farmonaut: contact us.