Scope: Japan only. Every site in this app is in Japan — the app is translated into 10 languages, but the map does not cover other countries.
A map of candidate collecting spots across Japan — places where you may be able to pick up stones — selected by cross-checking geological data with published occurrence records. It covers 17 minerals and fossils, including placer gold, amber, jade, topaz, obsidian, and fossil shark teeth.
■ Feels like a treasure hunt, grounded in geology
• The candidates start from records of real gold mines and localities (AIST's ore deposit data and the literature); their river courses and beaches are then traced with open data from the Geospatial Information Authority of Japan and AIST (rivers and coastline, geological maps, elevation, geochemical maps). Some starter gold packs include rivers with no gold record found nearby; the pack screen says so.
• Every spot shows the evidence for why it made the map: distance to the source rock, the nationwide percentile of its streambed geochemistry, even the terrain conditions.
■ Reading the map is simple
• Color = mineral, size = rank (by each pack's own measure), shape = type of place
• Placer gold is shown as points — way-markers to the river; everything else as bands (stretches of river or beach).
• Solid line = a stretch confirmed as beach or gravel bar with data; dashed line = a candidate stretch to verify on site
■ Start free
• The free placer gold area at Usotannai Gold Panning Park (Hokkaido), with 80 spots, works just like a paid pack: candidate spots, evidence, and trip logging are all included
• Also free, all of it: 27 hands-on facilities and officially sanctioned spots, the mineral field guide (how each mineral forms, identification tips, 20 varieties, 77 specimen photos), the shark tooth species guide (20 species) with a catalog of 9 localities, and 16 verification notes on localities and research notes (including records of trips where nothing was found)
• Paid packs are one-time purchases from ¥1,500 per pack — no subscription, no extra charges (the actual price is shown in your store's currency). Same price as the note articles. The app's sites and bands have been rebuilt from new river and coastline data
■ Made for the field
• All candidate data is built into the app. Locations, evidence, and trip logging work even with no signal.
• GPX export links up with hiking GPS apps
• Every spot shows an ease-of-access rating (distance from the road, slope)
■ Being honest with you
• This app is a map of candidates. It does not guarantee that you will find anything.
• Off-limits areas such as natural monuments are included too — clearly marked as no-collecting rather than hidden.
• Always check access and collecting rules for each location before you go.
Gold panning, rockhounding, beachcombing, fossil hunting — plan your weekend treasure hunt with records and sources as your guide.
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