43 CFR 3832.21 - How do I locate a lode or placer mining claim?
(a) Lode claims. (1) Your lode claim is not valid until you have made a discovery.
(2) Locating a lode claim. You may locate a lode claim for a mineral that:
(i) Occurs as veins, lodes, ledges, or other rock in place;
(ii) Contains base and precious metals, gems and semi-precious stones, and certain industrial minerals, including but not limited to gold, silver, cinnabar, lead, tin, copper, zinc, fluorite, barite, or other valuable deposits; and
(iii) Does not occur as bedded rock (stratiform deposits such as gypsum or limestone) or is not a deposit of placer, alluvial (deposited by water), eluvial (deposited by wind), colluvial (deposited by gravity), or aqueous origin.
(3) Establishing extralateral rights. If the minerals are contained within a vein, lode, or ledge and the vein, lode, or ledge extends through the endlines of your lode claim, you have extra-lateral rights to pursue the down-dip extension of the vein, lode, or ledge to the point where the vein, lode, or ledge intersects a vertical plain projected parallel to the end lines and outside the sideline boundaries of your lode claim if -
(i) The top or apex of the vein, lode, or ledge lies on or under the surface within the interior boundaries of the lode claim; and
(ii) The long axis, and therefore the side lines, of the lode claim are substantially parallel to the course of the vein, lode, or ledge.
(4) Preserving extralateral rights. In order to preserve your extralateral rights, you should determine, if possible, the general course of the vein in either direction from the point of discovery in order to mark the correct boundaries of the claim. You should expose the vein, lode, or ledge by -
(i) Tracing the vein or lode on the surface; or
(ii) Drilling a hole, sinking a shaft, or running a tunnel or drift to a sufficient depth.
(b) Placer claims. (1) Your placer claim is not valid until you have made a discovery.
(2) Each 10-acre aliquot part of your placer claim must be mineral-in-character.
(3) You may locate a placer claim for minerals that are -
(i) River sands or gravels bearing gold or valuable detrital minerals;
(ii) Hosted in soils, alluvium (deposited by water), eluvium (deposited by wind), colluvium (deposited by gravity), talus, or other rock not in its original place;
(iii) Bedded gypsum, limestone, cinders, pumice, and similar mineral deposits; or
(iv) Mineral-bearing brine (water saturated or strongly impregnated with salts and containing ancillary locatable minerals) not subject to the mineral leasing acts where a mineral subject to the General Mining Law can be extracted as the primary valuable mineral.
(4) Building stone deposits must by law be located as placer mining claims (30 U.S.C. 161). If you have located a building stone placer claim, the lands on which you located the claim must be chiefly valuable for mining building stone.