Many people think that you can file both a lode or placer for the opal deposits in Virgin Valley Nevada. They base this assumption on what has been done in the past or what other people have incorrectly told them. As the law requires, loose deposits (ie, erosional, alluvial or secondary) surface deposits MUST be located as PLACERs, while in-place (ie, source) subsurface opal bearing zones MUST be located as LODES. This law has been well-settled for over 100 years. It is also important to note that opals generally do not form economic placer deposits due to their fragile nature.
The precious opal in Virgin Valley is found "in-place" (where it was originally formed and deposited) within a hard, defined and traceable sub-surface horizon or zone of bentonite. The opal was deposited by hydrothermal fluids and silica rich water filling voids in the host bentonite matrix and as veins and fracture fillings of petrified wood. Bentonite has been defined as a mineral and consolidated clay rock derived from volcanic ash. Above and below the specific opal-producing zone, no commercially valuable deposit of opals are found to exist. The precious opals occur disseminated in-place throughout the opal bearing horizon or zone. This opal zone is followed by miners as a "lead." Because of "it's brittleness and low density, opal does NOT form economic placer deposits." See,The Geology of Gems by Eugenii Ya Kievlenko at page 124 (2003). "With the exception of some Brazilian material, gem opal is rarely found in alluvial gemstone placers, but is instead mined directly from its host rock." See,OPAL: The Phenomenal Gemstone, at page 11 (various contributors, Lithographie LLC 2007). "Alluvial opal deposits are rare and lie immediately on in situ deposits because opal cannot survive movement, as such, Placer opal deposits are unheard of."http://wy-opal.blogspot.com/.
This is not a recent dispute, it has been going on since the first claims were located in the valley and early claimants were able to secure one patent as a placer (Rainbow Ridge) for half the price (lodes cost $5 per acre, while placers cost $2.50 per acre). That is no defense, as LODES KNOWN TO EXIST ARE EXCLUDED from patented ground. If you are staking your own claim, buying a mining claim, leasing or digging on a claim, you need to know the law. A series of legal proceedings have begun and we will have a final decision within 6 months to 2 years.