The question comes up at every mining camp: lode or placer? Pick the wrong one and you could spend months working ground you have no legal right to mine. Pick the right one and the 1872 Act protects your location as long as you keep paying the annual fee.
Here's how to think about the distinction in practical terms — and when it gets complicated.
A lode claim is designed for mineral deposits that are in place — meaning still in the original rock formation they formed in. Classic lode targets include gold-bearing quartz veins, copper porphyry systems, silver-bearing sulfide deposits, and epithermal gold systems.
The 1872 Act allows a lode claim to extend 1,500 feet along the course of the vein and 300 feet on each side of the vein centerline, for a maximum of roughly 20 acres. Two people can locate a single lode claim as co-locators, but each person can only locate one additional lode claim on the same vein within the same 1,500-foot segment.
The legal requirement for a valid lode location is that you have actually discovered a vein or lode of quartz or other rock carrying valuable mineral. A real discovery — not just color in the soil — is required to make the location defensible.
If the gold has been physically moved from its original source rock by water, erosion, or gravity and deposited in a different location, it's placer gold. Stream gravels are the most obvious example — but ancient bench gravels high above the current stream, residual deposits at the base of a weathered vein, and eolian (wind-deposited) sands also qualify as placer deposits.
The size limits for placer claims are different. A single locator can claim up to 20 acres. Two people can claim 40 acres together. Eight or more people can combine to locate an association placer of up to 160 acres — a full PLSS section — in a single location act. This is the mechanism behind many of the large 160-acre claim blocks you see on MLRS maps.
The rule of thumb: if you found it by panning a stream, it's placer. If you found it by chipping at rock outcrops, it's lode. But a lot of real-world prospecting lands in a gray zone.
| Scenario | Correct Claim Type |
|---|---|
| Color in creek gravel | Placer |
| Gold in quartz vein outcrop | Lode |
| Ancient elevated bench gravel | Placer |
| Disseminated gold in altered granite | Lode |
| Gold in bedrock crevices near stream | Usually placer (if alluvial) |
| Gold-silver sulfide deposit at surface | Lode |
| Residual soil deposits over weathered vein | Can be either — consult BLM |
Courts have long held that if you locate a lode claim on ground that actually contains only placer deposits (or vice versa), the location is void. When in doubt, file both a lode and a placer on the same ground — the law allows this, and it costs only the additional filing fees to cover your bases.
A mill site claim covers non-mineral land used for processing, milling, or other support operations for a mining operation. Maximum size is 5 acres. The land must be non-mineral (no valuable deposit) and must be used or occupied for mining or milling purposes. Mill sites are separate locations from the mining claim — they protect your camp, processing area, or access route from competing locators.
The least used type, a tunnel site claim allows a prospector to drive a tunnel into a hillside to prospect for lode deposits. The tunnel gives the locator rights to any lode veins cut by the tunnel as it advances, with a possessory right to 3,000 linear feet of tunnel direction and 1,500 feet on either side. Once a vein is cut, a separate lode location is required to hold those rights.
AuthoriProspector overlays live BLM claims, 20-acre aliquot precision, USGS historic mine markers, and no-go zones on a single map. Tap any block to see who owns it — then stake and file from the field.
See BLM Claim Types on AuthoriProspector →