How GossanAtlas works, and where every number comes from
GossanAtlas shows the public record of what has been found, worked, leased and drilled in Tasmania, placed on a map that you can wind back through time. It is built by SupportCALL in Launceston. Nothing here is a survey, a title search, or advice to prospect, mine or invest.
What is fact and what is inference
Three kinds of thing appear on the map, and they are drawn differently so you can always tell them apart.
- Records (solid dots and polygons). Mineral occurrences, mines, prospects, boreholes, leases, licences, fossicking areas and the prospecting access classification, exactly as published by Mineral Resources Tasmania (MRT) in its TIGER database and tenement register. Each record carries MRT's own location accuracy in metres where MRT supplies it, and links back to the MRT record page and report references.
- Timeline discoveries (ringed dots). Dated discoveries, rushes and fields compiled from primary sources and checked one by one. Each row carries its verification status and its sources. Where a discovery could only be placed by locality or district, the ring is dashed.
- Assessments (dashed circles and the shaded grid). Computed by GossanAtlas from the records above using a documented, deterministic method that anyone can re-run. They never use a hidden model and never call an outside service. They are inferences, labelled as such, with the records that drove them listed in every popup.
The likely-location estimate
When a historical discovery has no exact coordinates, GossanAtlas looks for MRT occurrence records of the same commodity group whose name or locality matches the discovery, within 12 km for a locality-level entry or 30 km for a district-level entry. The matches are weighted by how well they match and by their status (a worked mine outweighs a bare occurrence). The weighted centre of the best matches becomes the likely location; the radius is the spread of those matches plus MRT's stated location accuracy, never less than 300 m and never more than 15 km. The popup names every record used. If no match exists, no estimate is drawn.
The prospectivity grid
The state is divided into 2 km cells. For each commodity group, every MRT metal occurrence within 6 km of a cell centre adds to the cell's score, decaying with distance (e-folding length 2 km), weighted by status (operating or abandoned mine 3 to 4, prospect 1.8, mineralised area or occurrence 1.2) and raised by up to 100 percent where the host unit or form matches the documented association for that commodity (for example Mathinna Supergroup turbidites and quartz veins for gold, Devonian granite, greisen and dolomite for tin, serpentinite and ultramafics for osmiridium and nickel, Mount Read Volcanics for base metals). Alluvial records add 30 percent for gold, tin and osmiridium. Drilling density adds a small amount as evidence of exploration interest. Scores are log-scaled and set so the 99th percentile cell for that commodity scores 100.
This is a knowledge-driven index overlay (the family of methods described by Yousefi and Carranza, Natural Resources Research 25, 2016, and by Bonham-Carter, Agterberg and Wright, Geological Survey of Canada Paper 89-9, 1989): the weights are stated, not learned, so the result is reproducible and arguable. MRT publishes its own machine-learnt prospectivity rasters for north-east Tasmania orogenic gold and for tin-tungsten; they are available as overlays and are a useful independent check. A high GossanAtlas score means "the public record is dense with this metal here", not "there is ore here".
Known limits: the grid does not yet use stream geometry, slope, geochemical sample assays or geophysical grids, all of which exist in the live overlays and are planned for the next assessment release. Scores inside national parks and other unavailable land are still computed, because the geology does not stop at a boundary, but the "Can I prospect here" check will tell you the land is closed.
Where did it come from: the source trace
Every alluvial record in the MRT database is snapped to the stream network on a 30 m elevation model (Copernicus GLO-30, resampled to 90 m), and the network is walked upstream for 15 km of flow path. The cells reached are the catchment that could have shed the find. Hard-rock records of the same commodity inside that catchment are listed as candidate sources, scored by flow distance, shared commodity and whether they were ever worked. Where there is none, the find is marked unexplained: the metal reached the creek from somewhere above, and the public record does not say where. The "Source targets" layer and the "Where to look" ranking add up the upper catchments of all unexplained finds, by commodity, into 2 km cells.
Constants: snap 300 m (700 m second look), stream threshold 30 cells, trace 15 km, score decay 8 km, candidate thresholds 0.8 known and 0.25 possible; the full method and its limits are in docs/METHOD.md section 4 of the installed package. The DEM is a surface model that misroutes flow on flat ground and in narrow gorges, and deep leads under basalt follow valleys it cannot see; treat the trace as a reading of the public record, not as a prediction of a lode.
Can I prospect here
Click anywhere on the map. GossanAtlas tests the point against MRT's statewide Prospecting Access classification (every parcel in Tasmania classified as allowed, permission required or not allowed), the declared fossicking areas, land unavailable under the Mineral Resources Development Act, current leases and licences, strategic resource areas and prospectivity zones, and reports the nearest metal records, watercourses and the cell's assessed scores. It then lists the rules that apply:
- Prospecting without a prospecting licence is an offence: Mineral Resources Development Act 1995 (Tas) s 107. A licence costs $39.20 per 12-month period from 1 July 2026 (Mineral Resources Regulations 2026); it was $38.20 in 2025-26.
- A licence allows prospecting on Crown land not under a tenement; tenement land needs the tenement holder's written consent; private land needs the owner's or occupier's consent: s 112(1).
- Declared fossicking areas need no licence (s 116); MRT's published conditions for fossicking areas apply and do not permit metal detectors.
- On reserved land, digging up or removing rock or mineral is prohibited and a metal detector may not be brought in: National Parks and Reserves Management Regulations 2019, reg 5(2)(c) and reg 5(10).
- Aboriginal relics: stop and report a find (Aboriginal Heritage Act 1975 (Tas) s 10(3)); do not disturb or remove (s 14). GossanAtlas never maps Aboriginal heritage sites.
The access verdict reflects the MRT dataset on the download date shown below. Land status changes. Always confirm with MRT and the landholder before entering land.
Data loaded into GossanAtlas
| Dataset | Custodian | Licence | Downloaded | Rows |
|---|---|---|---|---|
| Alluvial source traces (upstream catchments and candidate hard-rock sources) source | SupportCALL GossanAtlas research (derived from MRT TIGER occurrences and the Copernicus GLO-30 DEM) | Derived work: MRT inputs CC BY 3.0 AU; Copernicus DEM under the Copernicus DEM licence (free use with attribution) | 2026-11-05 05:50:11 | 1,141 |
| Borehole collar locations source | Mineral Resources Tasmania, Department of State Growth | Creative Commons Attribution 3.0 Australia | 2026-11-05 04:54:43 | 39,762 |
| Document index (open-file exploration and department reports) source | Mineral Resources Tasmania, Department of State Growth | Creative Commons Attribution 3.0 Australia | 2026-11-05 04:54:52 | 12,944 |
| Mineral occurrences (TIGER deposits database) source | Mineral Resources Tasmania, Department of State Growth | Creative Commons Attribution 3.0 Australia | 2026-11-05 04:54:24 | 8,298 |
| Named watercourses (LIST hydrology, via MRT service) source | Land Tasmania (theLIST), Department of Natural Resources and Environment Tasmania | Creative Commons Attribution 3.0 Australia | 2026-11-05 04:54:51 | 86,892 |
| Principal fossicking areas, points of interest, fossil sites source | Mineral Resources Tasmania, Department of State Growth | Creative Commons Attribution 3.0 Australia | 2026-11-05 04:54:52 | 13 |
| Prospecting access classification (all Tasmanian land) source | Mineral Resources Tasmania, Department of State Growth | Creative Commons Attribution 3.0 Australia | 2026-11-05 04:18:38 | 70,723 |
| Report footprints and historic mineral chart index (polygons) source | Mineral Resources Tasmania, Department of State Growth | Creative Commons Attribution 3.0 Australia | 2026-11-05 04:54:52 | 13,164 |
| Source target grid (where the hard-rock source of unexplained alluvial finds should be looked for) source | SupportCALL GossanAtlas research (derived from MRT TIGER occurrences and the Copernicus GLO-30 DEM) | Derived work: MRT inputs CC BY 3.0 AU; Copernicus DEM under the Copernicus DEM licence (free use with attribution) | 2026-11-05 05:50:11 | 3,829 |
| Tenements, fossicking areas, unavailable areas, strategic resources (polygons) source | Mineral Resources Tasmania, Department of State Growth | Creative Commons Attribution 3.0 Australia | 2026-11-05 04:54:42 | 18,740 |
| Verified discovery timeline (LodeAtlas research, 2026-11-05) source | SupportCALL (compiled from Mineral Resources Tasmania bulletins and records, Trove, Libraries Tasmania, Companion to Tasmanian History, ADB, company reports) | Compilation (c) SupportCALL; each row cites its public sources | 2026-11-05 04:54:52 | 139 |
Attribution as required by the custodians: Mineral Occurrences, Tenements and Land Management, Prospecting Access, Boreholes from Mineral Resources Tasmania (c) State of Tasmania, CC BY 3.0 AU. Hydrology and Topographic base map from theLIST (c) State of Tasmania, CC BY 3.0 AU (the hydrology lines are served through an MRT map service whose copyright field is blank; the CC BY 3.0 AU licence is taken from Land Tasmania's open data policy for theLIST hydrology). Each file's sha256 is recorded so a reload can be checked against the original download.
Live overlays (fetched from the custodian when you switch them on)
- Mineral Resources Tasmania imagery service: 1:25 000 and 1:250 000 geology, reduced-to-pole tilt magnetics, MRT's turbidite-hosted gold-antimony prospectivity model for north-east Tasmania and its granite-related tin-tungsten-fluorine prospectivity model. (c) State of Tasmania, CC BY 3.0 AU.
- Mineral Resources Tasmania map service: samples and observations (about 800 000 points, drawn by MRT's server at close zooms). (c) State of Tasmania, CC BY 3.0 AU.
- Copernicus DEM (source trace elevation, processed offline): produced using Copernicus WorldDEM-30 (c) DLR e.V. 2010-2014 and (c) Airbus Defence and Space GmbH 2014-2018 provided under COPERNICUS by the European Union and ESA; all rights reserved. Obtained from the AWS Open Data registry.
- Digital Earth Australia (c) Commonwealth of Australia (Geoscience Australia): Landsat annual geomedian and Sentinel-2 imagery as base maps, ASTER ferric oxide content and kaolin group index. CC BY 4.0. Sentinel-2 contains modified Copernicus Sentinel data 2015-present.
- theLIST (Land Tasmania): topographic and grey topographic base maps. CC BY 3.0 AU.
Your browser fetches these directly from the custodian. GossanAtlas does not proxy, cache or store them, and does not use Google, OpenStreetMap or other tile services whose terms do not permit this use.
Free-to-use sources you can read further
- Mineral Resources Tasmania: TIGER database searches for deposits, documents, drill holes and samples; the Geoscience Library; open-file company reports.
- MRT prospecting and fossicking: licence applications, fees, conditions and the official Prospecting Access map.
- LISTmap: cadastre, reserves, topography and historic charts.
- Geoscience Australia portal and ELVIS for LiDAR elevation that reveals old workings under forest.
- Trove: digitised newspapers reporting the original rushes, and Libraries Tasmania archives.
- Field knowledge: Rob Parsons and Tassie Boys Prospecting on YouTube document Tasmanian goldfields, rivers and ruins on the ground. GossanAtlas links to channels; it does not copy, embed without consent, or scrape video content.
Field mode, offline packs and the emergency sheet
Field mode (bottom right of the map) uses your phone's GPS to show your position in decimal degrees and MGA zone 55 easting and northing (GDA2020, which matches GPS WGS84 to within a metre), keeps a track log, lets you mark waypoints, and gives a live distance and bearing to a chosen waypoint with a turn arrow once a compass heading is available. Alerts fire on arrival at a waypoint, when position accuracy is poor, and when you move onto land where prospecting is not allowed or needs permission (checked against the MRT access data every 45 seconds while tracking). Track, waypoints and contact details stay on your device; export them as GPX whenever you like.
Offline packs (the dot beside the search box) download an area's records, tenements, prospecting access parcels, creeks, drill holes, prospectivity cells and the topographic base map into your browser. With no signal the map, search, record panels and "Can I prospect here" keep working from the pack and say so in the panel. Add GossanAtlas to your home screen for a full-screen app that opens offline.
Emergency (red button in the top bar) shows a one-tap call to 000, your position in words you can read out, and lets you text or email a saved emergency contact with your position using your phone's own apps. Signed-in members can also have the GossanAtlas server email the contact and the administrator. None of this replaces calling 000. Browsers pause GPS when the screen is off, so keep the screen on while tracking, carry a paper map and a PLB in remote country, and tell someone your plan.
Tenement changes, alerts and exports
Mineral Resources Tasmania updates its current leases and licences daily. GossanAtlas re-reads that register every day, records what changed (new tenements, tenements that left the register, holder, status, dates and extent), moves lapsed tenements into the historic layer so the time strip stays true, and shows the last 90 days of changes as a map layer. Members can draw an alert area and receive one email a day when anything changes inside it. Any view can be downloaded as CSV with the custodian attribution on the first line.
Accounts and privacy
The map and every record are public. An account adds pins, saved views and the record assistant. We store your name, email and password hash (Argon2id), the pins and views you create, and an audit trail of sign-ins. Your GPS position is never sent to GossanAtlas unless you press an emergency send button or run a land check while tracking (which sends only the coordinates of that check). Members cannot see each other's details. We send one approval email and nothing else unless you ask. SupportCALL operates as a sole trader under the Privacy Act 1988 (Cth) small business threshold and nonetheless handles your information in line with the Australian Privacy Principles. To see or delete your data, email info@davidmaree.com.