Satellite Gold Map: What It Shows and How to Read One

A satellite gold map shows where imagery picks up the surface signs that commonly accompany gold mineralisation: hydrothermal alteration minerals, iron oxides, silicification and ore-controlling structures. Those zones are ranked so explorers know where to sample first. It is a targeting tool. It narrows a search from an entire licence or district to a handful of zones worth walking, sampling and eventually drilling.

Try it: How much gold sits in one satellite pixel? →

That distinction matters, because the phrase “gold satellite map” is used for very different things online. There are phone apps that promise to “detect gold”, simple Google Earth views of old workings, historical mine-occurrence databases, and genuine spectral and structural analyses built from multispectral and hyperspectral data. Only the last one tells you anything new about the ground, so that is the kind we explain and help you judge.

“Nevada produced about 70% of US mined gold, according to the USGS.”

What a satellite gold map actually detects

Floyd Sabins’ widely cited review in Ore Geology Reviews identified the two jobs remote sensing does in mineral exploration: mapping the geology, faults and fractures that localise ore, and recognising hydrothermally altered rocks by their spectral signatures. A satellite gold map combines both, applying to one metal the methods our wider guide to geology and remote sensing with Landsat, ASTER and Sentinel-2 covers for every commodity. The surface features it looks for depend on the deposit type, but most fall into a few groups.

• ✔ Iron oxides and gossans: hematite, goethite and jarosite formed where sulphides such as pyrite weathered at surface. Visible in the visible and near-infrared bands.
• ✔ Clay and mica alteration: sericite (fine muscovite), illite, kaolinite and alunite formed by hydrothermal fluids. Detected by shortwave-infrared (SWIR) absorption near 2.2 µm.
• Carbonate and chlorite alteration: common around orogenic gold in greenstone belts; SWIR absorption near 2.3 µm.
• Silicification: quartz veins and silica caps, best mapped in thermal-infrared bands.
• Structures: shear zones, faults, fold hinges and fracture intersections, mapped from elevation data, radar and enhanced imagery.
• ⚠ Not gold itself: any product that claims to show gold directly from orbit deserves scepticism.

A study of the Ngoura-Colomines goldfield in eastern Cameroon, published in Ore Geology Reviews, shows the approach. Researchers used Landsat-8 and ASTER imagery to map alteration associated with gold-bearing quartz veins (pyritisation, muscovite/sericite, iron oxides and silicification) and combined the layers into prospectivity maps. They also noted the main challenge in tropical and sub-tropical terrain: climate and vegetation constrain what optical satellites can see.

Is there such a thing as a satellite gold detector?

Not in the sense the apps imply. Search for a “satellite gold detector” and you will find tools that promise to point at buried gold. Satellites measure reflected and emitted light from the top of the ground. What they can do is detect the alteration and structure around a gold system, which is a real and useful signal, but a different claim entirely. The same caution applies on the ground, where “long-range locators” are often sold beside real radar; our guide to what ground penetrating radar can and can’t find separates the two.

The data behind every satellite gold map

Most satellite gold maps are built from a small number of sensors. Knowing them helps you judge what a given map can and cannot show.

Free multispectral: Landsat and Sentinel-2

The US Geological Survey made the entire Landsat archive free in 2008. Landsat 8 and 9 record nine bands at 30 m, including two SWIR bands that support iron-oxide and clay ratios. ESA’s Sentinel-2 records 13 bands at 10, 20 and 60 m, with a revisit of about five days at the Equator, and Copernicus data are free and open too. These are the free base layer under almost every gold satellite map. They are excellent for regional screening and iron oxides but have only two SWIR bands, so they detect “clay-type” alteration without identifying the specific mineral.

ASTER: the alteration workhorse

ASTER, on NASA’s Terra satellite, records 14 bands including six in the SWIR and five in the thermal infrared, with pixels from 15 to 90 m. That SWIR detail separates sericite, kaolinite, alunite, chlorite and carbonate far better than Landsat or Sentinel-2. The SWIR detectors failed in April 2008, but the archive before then remains one of the most useful free datasets for gold alteration mapping. In Australia, CSIRO and Geoscience Australia used ASTER to build the first continent-scale maps of surface mineralogy.

Hyperspectral and commercial imagery

Hyperspectral sensors record hundreds of narrow bands and can identify individual mineral species, including subtle changes in white-mica chemistry that some gold systems show. Germany’s EnMAP works at 30 m and NASA’s EMIT at about 60 m. Commercial satellites add metre-scale resolution for mapping small outcrops, veins, old workings and access. These data cost money per square kilometre, so most programs buy them only for the targets that the free data have already narrowed down. Spending in that order keeps imagery costs proportional to the evidence.

Plot the free and scientific sensors’ pixel sizes side by side and the trade-off is obvious: the sharpest free pixels (Sentinel-2 at 10 m) come with the fewest SWIR bands, while ASTER’s alteration-friendly SWIR bands sit at 30 m and its thermal bands at 90 m.

Here is the arithmetic behind the “no satellite sees gold” rule. The estimator takes an ore grade, a pixel size and the thin surface layer an optical sensor reads, and shows how much gold that pixel actually contains compared with the rock around it.

How a satellite gold map is built, step by step

The process behind a professional satellite gold map is similar whoever builds it. Knowing the steps helps you ask the right questions of any map you are shown.

1. Define the area and the model. The licence polygon, the country, and the expected gold deposit style (orogenic, epithermal, porphyry-related, intrusion-related or placer) decide what to look for.
2. Select and prepare imagery. Cloud-free, preferably dry-season scenes are corrected to surface reflectance, and vegetation, water and cloud are masked.
3. Map alteration. Band ratios, principal components and, for hyperspectral data, spectral matching highlight iron oxides, clays, micas, carbonates and silica.
4. Map structure. Lineaments, shears, fold hinges and fracture intersections are traced from elevation models, radar and enhanced images.
5. Integrate and rank. Alteration, structure and known geology are combined, often with fuzzy-logic or machine-learning models as in the Cameroon study, into a prospectivity map.
6. Validate. Anomalies are checked across multiple dates and against geology to remove look-alikes, then handed over for field checking.

Satellite imagery and gold exploration by deposit type

Gold forms in several very different geological settings, and a good satellite gold map is tuned to the one expected in your area.

Orogenic (shear-hosted) gold

Common in the greenstone belts of West and East Africa, Western Australia and the Canadian Shield. Gold sits in quartz veins along shear zones, with sericite, carbonate, chlorite and iron-oxide alteration that is often narrow. Structural mapping of the shears, their bends and intersections usually matters more than the spectral signal. The Cameroon study found gold-bearing veins with pyritisation, sericite, iron oxides and silicification.

Epithermal gold-silver

Formed near the surface in volcanic terrains. Alteration can be broad and spectrally distinctive (alunite, kaolinite, silica caps), which makes epithermal systems among the best targets for SWIR and thermal satellite mapping.

Porphyry-related gold

Gold with copper in large intrusive systems shows concentric alteration zoning (potassic cores, sericite shells and outer clay and chlorite zones) plus iron-oxide caps, all visible to ASTER-class sensors in well-exposed terrain.

Placer and paleochannel gold

Gold eroded from bedrock and concentrated in rivers and old channels. Satellite maps help here in a different way: mapping drainage networks, terraces, old channels and the bedrock sources upstream, rather than alteration.

Regional context: Africa and Asia

Satellite gold maps are most useful where there is the most exposed prospective ground. The USGS Mineral Commodity Summaries for gold list Ghana (about 130 t in 2024), South Africa (about 100 t), Mali (about 70 t), and Tanzania and Burkina Faso (about 60 t each) among significant African producers. Much of that gold comes from greenstone belts and shear zones where alteration and structure can be mapped from orbit, although vegetation and deep weathering in wetter regions complicate the picture.

In Asia, the same USGS summary lists China (about 380 t) as the largest producer, with Kazakhstan (about 130 t), Uzbekistan (about 120 t) and Indonesia (about 100 t) also significant. Central Asia’s arid belts suit spectral alteration mapping well. Tropical Indonesia, like much of equatorial Africa, is a case where cloud and vegetation push explorers towards radar, elevation and structural analysis alongside optical data.

The United States: Nevada, Alaska and a shrinking total

The USGS reports that Nevada accounts for about 70% of US mined gold and Alaska about 16%, with gold produced at more than 40 lode mines in 12 states and at placer mines mostly in Alaska and the western states. National mine output has slipped every year in the USGS series, from 193 t in 2020 to an estimated 160 t in 2024. Nevada’s arid, well-exposed terrain is close to ideal for spectral alteration mapping; Alaska’s boreal cover and snow make structural and drainage analysis relatively more important.

Google Earth views versus spectral gold maps

Many people first look for gold on Google Earth, and it is genuinely useful: true-colour imagery shows old workings, outcrops, colour changes in soil, drainage and access tracks. What it cannot show is the infrared part of the spectrum where clay, mica and carbonate alteration minerals have their diagnostic absorption features. A spectral satellite gold map uses exactly those invisible bands. The two work well together: use spectral analysis to find and rank targets, then high-resolution true-colour imagery to plan how to reach them.

How to read a satellite gold map

A satellite gold map usually arrives as a set of coloured layers over imagery, plus a ranked target list. A few habits make it much more useful, and make it harder for a weak product to impress you.

Check the legend and the basis for each layer

Each layer should say what it shows: iron-oxide index, clay or sericite index, silica, lineament density, or a combined prospectivity score. Colour stretches exaggerate, so a vivid red patch can be a small absolute change. Ask what threshold was used and why.

Look for agreement between independent evidence

The strongest targets are where two or three independent lines of evidence coincide: alteration minerals, a favourable host rock and a structure such as a shear bend or fault intersection. A clay anomaly on its own, in the middle of a flat valley, is weak evidence.

Compare with the ground you actually hold

Overlay the licence boundary, known workings, roads, villages, farmland and protected areas. A target that sits across a boundary or under a settlement changes how you plan fieldwork and negotiations.

Read the confidence and the caveats

A good satellite gold map ranks its targets and says which are strong and which need more work. It also states what it cannot see (areas masked by vegetation, cloud or cover) so you know where the absence of a target means “not tested” rather than “nothing there”.

Free gold map resources, and what they don’t tell you

Several free resources are often described as a gold satellite map. They are useful, but they answer different questions from a spectral prospectivity map.

• Mineral occurrence databases: the USGS Mineral Resources Data System (MRDS) lists mineral sites with location, commodity and deposit description, and can be filtered to show gold. Many national geological surveys publish similar occurrence maps. They show where gold has been recorded, not where it has not yet been found.
• Government geology maps: the host rocks and structures that matter for gold. Often old or coarse in remote areas.
• Free satellite viewers and archives: Landsat and Sentinel-2 imagery through official portals. You can build basic iron-oxide and clay composites yourself.
• 📊 Satellite maps of mining activity: conservation groups such as MAAP use satellite imagery, including monthly 4.7 m Planet NICFI mosaics, to track gold-mining deforestation in the Peruvian Amazon. These show where mining is happening, not where gold remains.

“USGS estimates world gold mine production at about 3,300 tonnes for 2024.”

Before you buy any satellite gold map: a quick checklist

• ✔ Named data sources and dates of the imagery used.
• ✔ A described method for alteration and structural mapping, not a black box.
• GIS files you can load and check, not only screenshots.
• Ranked targets with reasons and a stated level of confidence.
• Honest limitations and a recommended field program.
• ⚠ Walk away from anyone who guarantees gold, quotes grades without samples, or offers to sell you “proven” ground based on imagery alone.

Limitations: where satellite gold maps go wrong

Every satellite gold map carries the same core limitation: optical sensors read the surface, not the subsurface. Knowing the failure modes lets you use a map well.

• ⚠ Vegetation and cover: dense forest, crops and transported sand hide bedrock. The Cameroon researchers explicitly note that climate and vegetation constrain optical imagery in tropical regions. Structural mapping and seasonal imagery help, but some areas need soil geochemistry or geophysics.
• ⚠ Deep weathering: laterite and iron-rich soils produce iron-oxide anomalies that have nothing to do with gold.
• Look-alikes: clay-rich sediments, dry lake beds and weathered shales can mimic alteration.
• Small targets: narrow veins sit well below a 30 m pixel. The halo is what you map, not the vein.
• Depth: any depth estimate in a satellite product is model-based. It guides drill planning; it is not a measurement.

One of the simplest defences against false targets is time. Burn scars, wet soil, crop residue and seasonal flooding come and go; alteration minerals in bedrock do not. Anomalies that persist across several dry-season scenes from different years are much more likely to be geological. That is why seasonal anomaly validation is part of how we check targets before they appear in a satellite gold map, and why a map built from a single scene deserves extra scrutiny.

Our satellite gold maps: what you send and what you get

Our satellite-based mineral detection applies this approach to your own ground. We analyse multispectral and, where suitable, hyperspectral imagery (each mineral and alteration zone reflects energy in its own spectral signature) and process it through our own algorithms to flag likely mineralised target zones, alteration halos, faults and fractures, and deposit-associated geological patterns.

• What you send: coordinates, a KML/KMZ file or a polygon, plus the country and target mineral.
• Turnaround: 5–20 business days, depending on area size and mineral complexity.
• 📊 Premium report: high-potential zones, prospectivity heatmaps, estimated location and depth ranges, indicative quantity, geological interpretation (faults, alteration, host rock), seasonal anomaly validation, and PDF plus georeferenced GIS files.
• 📊 Premium+: adds TargetMax™ Drilling Intelligence: optimal drilling-angle recommendations and interactive 3D subsurface models of vein structures and mineral distribution.
• 📊 Why screen first: exploration timelines from months to days, and up to 80–85% lower early-exploration cost, with no ground disturbance.
• ⚠ What it is not: a resource estimate or a guarantee of gold. It tells you where to sample and drill first.

We have scanned 100,000+ hectares for 20+ mineral types across 25+ countries in Africa, the Americas, Asia and Australia. See a sample of satellite-driven 3D mineral prospectivity mapping, or request pricing through the mining query form.

From satellite gold map to field program

1. Review the ranked targets with a geologist against the public geology map and any known occurrences.
2. Plan a field visit to the top targets: map outcrop, alteration and veining, and collect rock-chip samples.
3. Run soil or stream-sediment sampling where cover hides bedrock.
4. Add targeted geophysics, such as ground magnetics or IP, over the best confirmed zones.
5. Drill-test the targets that survive, using the structural interpretation to orient holes.
6. Feed results back into the map: each field check improves the interpretation of the rest.

Frequently asked questions

Reviewed September 2026 against the USGS Mineral Commodity Summaries 2025 gold chapter, the USGS EROS note on the free Landsat archive, ESA’s SentiWiki Sentinel-2 specification, NASA JPL’s ASTER SWIR notice, CSIRO’s national ASTER geoscience map, the USGS MRDS database, MAAP’s Peruvian Amazon gold-mining reports, Sabins (1999) and the Ngoura-Colomines study in Ore Geology Reviews.

Production figures are USGS estimates for 2024 and are revised in each annual edition, so check the latest Mineral Commodity Summaries for newer numbers. Satellite-derived gold targets are exploration targets, not mineral resources or reserves, and must be confirmed by field sampling and drilling. Nothing here is investment advice.