There have been many court cases and decisions as to what constitutes the discovery of a valuable mineral deposit and it can be a difficult and complicated matter. The general rule is stated in the famous _Castle_ v. _Womble_ Decision, 19 L.D. 455, 1894: “When minerals have been found and the evidence is of such a character that a person of ordinary prudence would be justified in the further expenditure of his labor and means, with a reasonable prospect of success, in developing a valuable mine, the requirements of the statute have been met.” In the Jefferson-Montana Copper Mines Co. case, 41 L.D. 320, 1902, it was stated that the following elements of discovery are necessary: “1. There must be a vein or lode of quartz or other rock in place. 2. The quartz or other rock in place must carry gold or some other valuable mineral deposit. 3. The two preceding elements, when taken together, must be such as to warrant a prudent man in the expenditure of his time and money in the effort to develop a valuable mine.” The extent of discovery will vary with the situation to be considered and the type of mineral and deposit. For example, the requirement as between two claimants is far less than that between a claimant and the United States. A mineral of intrinsic value such as gold may well be considered under the rules set forth above, but a more common mineral would be further subjected to a test of marketability. In the course of patent proceedings, a mineral examiner of the Bureau of Land Management, the Forest Service if the claim is in a national forest or the National Park Service if the claim is in a national park or monument, will make a field investigation to determine the validity of the claims in question. Each location must be shown to be more valuable for minerals than for any other purpose and the burden of proof rests with the claimant. The claimant must be prepared to show the actual physical discovery and substantiate the value through assays, drill logs, etc. The discovery need not be on the surface and may be made underground. In the case of blanket (horizontal) veins, the vein may be wider than the claim and discovery can be made anywhere within its boundaries. A discovery showing value and/or marketability may be anywhere within the claim. The discovery may be on the end line of a claim, but a single discovery cannot support more than one claim. A discovery may be lost by the patenting of a junior claim in conflict, in which case a new discovery is required. A claim cut in two by a non-mineral patent requires a discovery on each portion of the claim. A claimant is entitled to possession as against third parties as long as he is diligently engaged in trying to make a discovery. =2–2= Discovery Work: 43 C.F.R. 3841.3–2 states: