MINING CLAIMS GLOSSARY

Claim Types

Unpatented Mining Claim

A possessory interest in federal land that grants the holder the right to extract minerals, but the land itself remains under federal ownership. The claimant holds mineral rights subject to annual maintenance requirements. Unpatented claims are the primary record type in BLM MLRS and the focus of all ClaimWatch reports.

Patented Mining Claim

A mining claim that has been converted to full private ownership through the federal patent process. The patent conveys both surface and mineral rights from the federal government to the claimant. The patent process for new claims has been under a congressional moratorium since 1994, so no new patents are being issued.

Lode Claim

A mining claim for veins, lodes, or ledges of mineralized rock found in place. Lode claims are rectangular, up to 1,500 feet along the vein and 600 feet wide (300 feet on each side of the centerline). They are the most common claim type for hard-rock mineral deposits.

Placer Claim

A mining claim for loose, unconsolidated mineral deposits — typically alluvial gold, gemstones, or other minerals found in stream gravels, sand, or other surface material. Placer claims are described by aliquot parts of PLSS sections and are limited to 20 acres per individual claimant (160 acres for an association of 8 or more persons).

Millsite

A claim for up to 5 acres of non-mineral land used in connection with mining operations — typically for processing facilities, tailings areas, or support infrastructure. A millsite must be associated with a valid lode or placer claim and must be on land that is itself not valuable for minerals.

Tunnel Site

A right-of-way claim for a tunnel being driven to develop a lode or lodes. The tunnel site grants the right to all veins or lodes discovered within 3,000 feet of the tunnel face that were not previously known to exist. Tunnel sites are rare in modern practice.

Federal Agencies & Systems

BLM (Bureau of Land Management)

The federal agency within the U.S. Department of the Interior responsible for managing public lands, including the administration of mining claims on federal land. BLM maintains the official records for all unpatented mining claims through its MLRS system.

MLRS (Mineral and Land Records System)

BLM's online database system for recording and managing mining claims, mineral leases, land patents, and other land records. MLRS replaced the legacy LR2000 system and is the authoritative source for unpatented mining claim data in the United States. ClaimWatch draws its claim data from MLRS.

USGS (United States Geological Survey)

A scientific agency within the U.S. Department of the Interior responsible for studying the landscape, natural resources, and natural hazards of the United States. USGS maintains mining district boundary polygons and mineral deposit records used in ClaimWatch reports for geologic context.

CadNSDI (Cadastral National Spatial Data Infrastructure)

BLM's official GIS dataset for the Public Land Survey System. CadNSDI provides the authoritative digital geometry for townships, sections, and survey boundaries used to locate mining claims spatially. ClaimWatch uses CadNSDI data for all PLSS-based spatial analysis.

Public Land Survey System

PLSS (Public Land Survey System)

The surveying system used to subdivide and describe most land west of the original thirteen colonies. PLSS divides land into a grid of townships, ranges, and sections using a system of principal meridians and baselines. Nearly all federal mining claims are located and described using PLSS coordinates.

MTRS (Meridian-Township-Range-Section)

The four-component coordinate used to identify a specific PLSS section. For example, "Mt. Diablo Meridian, T15N R20E Section 14" identifies a single square-mile section of land. MTRS is the primary locator used in ClaimWatch to organize claim data.

Township

A six-mile-square area in the PLSS, identified by its north-south position relative to a baseline. A township contains 36 sections. Designated as "T" followed by a number and direction (e.g., T15N = Township 15 North).

Range

The east-west designation in the PLSS, measured from a principal meridian. Designated as "R" followed by a number and direction (e.g., R20E = Range 20 East).

Section

A one-square-mile (640 acre) subdivision of a township. Sections are numbered 1 through 36 in a serpentine pattern starting from the northeast corner. Sections are the primary unit of analysis in ClaimWatch reports.

Aliquot Part

A subdivision of a section described by halves and quarters. For example, "NE 1/4 SW 1/4" describes a 40-acre parcel. Aliquots are used to describe placer claim boundaries and to locate claims within a section at finer resolution than the section level.

Principal Meridian

A reference line running north-south from which ranges are measured in the PLSS. There are 37 principal meridians in the United States. Each mining claim is associated with a specific principal meridian (e.g., Mt. Diablo, Willamette, Salt Lake).

Mining Law & Regulations

General Mining Act of 1872

The federal law (30 U.S.C. 22-54) that authorizes U.S. citizens to locate mining claims on federal public domain land that is open to mineral entry. The Act establishes the legal framework for lode and placer claims, discovery requirements, and the patent process. It remains the foundational statute governing hardrock mining on federal land.

43 CFR (Title 43, Code of Federal Regulations)

The section of the Code of Federal Regulations that contains BLM's rules governing public lands, including detailed regulations for mining claim location, maintenance, recording, and administration. Part 3830-3839 covers mining claims specifically.

Discovery

The legal requirement that a valuable mineral deposit must be found within the boundaries of a mining claim to support its validity. A valid discovery requires that a prudent person would be justified in further expenditure to develop the deposit. Discovery is the legal foundation of an unpatented mining claim.

Location

The act of establishing a mining claim on federal land. Location involves physical marking of the claim boundaries on the ground (staking), filing a location notice with the county recorder, and recording the claim with BLM. The location date establishes the claim's priority or seniority.

Mineral Entry

The right to locate mining claims on public domain land. Land that is "open to mineral entry" can receive new mining claims. Withdrawals, wilderness designations, and other federal actions can close land to mineral entry.

Withdrawal

A federal action that removes public land from one or more forms of disposal, including mineral entry. Withdrawn land cannot receive new mining claims. Withdrawals may be temporary or permanent and can be made for military, conservation, or other purposes. Withdrawal overlays are a standard component of ClaimWatch Area Check reports.

Claim Administration

Maintenance Fee

An annual fee of $200 per claim (as of 2025) required to be paid to BLM to keep an unpatented mining claim in good standing. The fee is due on or before September 1 of each year. Failure to pay results in the claim being declared void by operation of law under 30 U.S.C. §28i. The maintenance fee system replaced the assessment work requirement in 1993. A 2011 legislative drafting error temporarily broke the fee system for pre-1993 lode claims, creating the AY2013 gap year exposure that ClaimWatch now tracks.

Assessment Work

Prior to 1993, claimants were required to perform at least $100 worth of labor or improvements on each claim annually to maintain it. Assessment work was replaced by the maintenance fee for most claimants, though a small-miner exemption (10 or fewer claims) still allows assessment work in lieu of the fee.

Disposition

The legal action recorded against a mining claim in BLM MLRS. Dispositions include actions like amendments, transfers, closures, voidances, and contest proceedings. Each disposition has a specific abbreviation code in MLRS.

Case Serial Number

The unique BLM identifier assigned to each mining claim when it is recorded in MLRS. The serial number consists of a state abbreviation, office code, and sequential number (e.g., NV-035-12345). This is the primary key for looking up a specific claim in BLM records.

Claim Seniority

The priority of a mining claim relative to other claims, determined by the location date. Earlier claims have senior rights. Seniority is critical where claims overlap — the senior claim generally controls the disputed ground. Claim seniority is analyzed in ClaimWatch Area Check reports. ChoraQuest's GroundControl tools provide detailed overlap resolution for complex seniority disputes.

Land Status

The legal status of public land with respect to availability for mining claim location and other forms of mineral entry. Land status is determined by withdrawals, reservations, classifications, and other federal actions. BLM land status verification is a core component of ClaimWatch Area Check reports.

Industry Terms

Mining District

A geographic area, often defined by historic mining activity, within which local rules and customs for mining claim location were established. USGS maintains boundary polygons for over 2,100 historic mining districts across 37 states. Mining district context is a core component of ClaimWatch Regional Prospecting & Site Selection reports.

Due Diligence

The investigation and verification of mining claims, land status, and mineral rights prior to acquisition, investment, or development. ClaimWatch's Area Check report is purpose-built for claim-level due diligence.

Site Selection

The process of evaluating and ranking candidate parcels within a region for mineral exploration or development. ClaimWatch's Regional Prospecting & Site Selection report provides scored comparison of candidate parcels based on mineralization, competitive position, and land status.

Claim Staking

The physical process of marking mining claim boundaries on the ground using posts, monuments, or other markers, combined with filing the required notices with the county recorder and BLM. ChoraQuest's automated staking tools can generate complete staking packages at scale.

Mineral Title Examination

A comprehensive review of the chain of title for mineral rights on a specific parcel, including unpatented claims, patented claims, mineral reservations, and encumbrances. Title examination goes beyond ClaimWatch's intelligence reports into full legal-grade analysis, provided through ChoraQuest's professional services.

Geology & USGS Terminology

Mineral Deposit

A naturally occurring concentration of minerals in the earth's crust that is of sufficient size, grade, and accessibility to be of potential economic interest. Mineral deposits are classified by formation type (lode, placer, disseminated, massive, vein, skarn, porphyry, etc.) and by commodity (gold, silver, copper, lithium, etc.). USGS maintains records of documented mineral deposits across the United States, and ClaimWatch uses these records to provide geologic context in Regional Prospecting and Area Check reports.

Lode Deposit

A mineral deposit occurring in a vein, ledge, or other rock formation in place. Lode deposits are the target of lode mining claims and are typically hard-rock deposits where mineralization occurs within a defined structure such as a quartz vein, fault zone, shear zone, or contact zone between rock types. The term distinguishes in-place rock-hosted deposits from loose surface material (placer deposits).

Placer Deposit

A surface or near-surface accumulation of heavy minerals (typically gold, platinum, gemstones, or tin) that have been concentrated by gravity, water, or weathering processes. Placer deposits form in stream beds, alluvial fans, beach sands, and ancient river channels where dense mineral grains settle out of flowing water. Placer mining claims are described by aliquot parts of PLSS sections.

Vein

A tabular or sheet-like body of minerals that fills a fracture or fault in the host rock. Veins are a common type of lode deposit and are often composed of quartz with associated metallic minerals (gold, silver, base metal sulfides). The orientation, width, continuity, and mineral content of veins determine the size and shape of lode mining claims.

Mineralization

The geological process by which minerals are introduced into a rock body, or the result of that process. Mineralization can occur through hydrothermal fluids, magmatic intrusion, sedimentary deposition, or weathering. In exploration, "mineralization" refers to the presence of economically interesting minerals in rock, whether or not the concentration is sufficient to constitute an ore deposit.

Prospectivity

A measure of how likely an area is to contain economically viable mineral deposits, based on geological, geochemical, geophysical, and historical indicators. ClaimWatch's Regional Prospecting reports assess prospectivity at the PLSS section level by combining USGS mineral deposit records, active claim density, mining district proximity, and historic production data.

Ore

Rock or earth material from which a valuable metal or mineral can be profitably extracted. What constitutes "ore" depends on the commodity price, extraction costs, processing technology, and regulatory environment. A mineral deposit becomes an ore deposit when extraction is economically feasible.

Critical Minerals

Minerals deemed essential to economic and national security, with supply chains vulnerable to disruption. The USGS maintains the official U.S. critical minerals list, which includes lithium, cobalt, rare earth elements, antimony, graphite, manganese, and others. Exploration for critical minerals on federal land follows the same claim location process as traditional hardrock mining under the General Mining Act of 1872.

Commodity

The specific mineral or metal that is the target of exploration or mining activity. Common commodities in western U.S. mining include gold, silver, copper, molybdenum, lithium, uranium, and tungsten. BLM MLRS records the commodity type associated with each mining claim, and ClaimWatch reports include commodity analysis as part of the geologic framework.

MRDS (Mineral Resources Data System)

A USGS database of mineral deposit records across the United States and worldwide. MRDS contains location, commodity, deposit type, production history, and geologic setting information for documented mineral occurrences. ClaimWatch uses USGS mineral deposit data to provide geologic context and prospectivity indicators in reports.

Geologic Map

A map showing the distribution of rock types, geologic structures (faults, folds, contacts), and surficial deposits across an area. Geologic maps are fundamental tools in mineral exploration because mineral deposits are controlled by specific rock types and structures. USGS publishes geologic maps at various scales across the United States.

Fault

A fracture in the earth's crust along which rock masses have moved relative to each other. Faults are significant in mining because they can serve as conduits for mineralizing fluids (creating vein deposits), as boundaries between different rock types, and as structural traps that concentrate mineral deposits. Fault zones are common targets for lode claim locations.

Alteration

Chemical and mineralogical changes in rock caused by hydrothermal fluids, weathering, or other geologic processes. Hydrothermal alteration (silicification, argillic alteration, propylitic alteration, potassic alteration) is a key exploration indicator because it signals that mineralizing fluids have passed through the rock. Alteration halos around mineral deposits are often larger than the deposit itself, making them useful exploration targets.

Assay

A quantitative analysis of a rock, soil, or sediment sample to determine the concentration of specific metals or minerals. Assay results are reported in parts per million (ppm), grams per tonne (g/t), ounces per ton (oz/ton), or percentage. Assay data is used to evaluate whether a mineral occurrence has economic potential and to define ore grade within a deposit.

Outcrop

An exposure of bedrock or other geological material at the earth's surface. Outcrops provide direct observation of rock type, structure, mineralization, and alteration without drilling or excavation. In mining claim research, outcrop observations are often the basis for initial discovery and claim location.

Host Rock

The rock formation that contains or surrounds a mineral deposit. The type of host rock (granite, limestone, volcanic tuff, metamorphic schist, etc.) influences the deposit type, grade, geometry, and extraction method. Understanding the host rock is essential for exploration targeting and claim layout.

Strike and Dip

The orientation of a geological feature (bed, vein, fault, or contact) in three-dimensional space. Strike is the compass direction of the feature's intersection with a horizontal surface. Dip is the angle of inclination from horizontal, measured perpendicular to strike. Strike and dip are used to describe vein orientations and to project mineral structures at depth, which directly affects how lode claims are laid out relative to the vein.

Porphyry Deposit

A large, low-grade mineral deposit associated with porphyritic intrusive igneous rock. Porphyry deposits are the world's primary source of copper and molybdenum and can also contain gold and silver. They are typically large-tonnage, disseminated deposits that require open-pit mining and are associated with extensive alteration halos. Porphyry systems in the western U.S. are common targets for large-scale claim blocks.

Epithermal Deposit

A mineral deposit formed at shallow depth (less than 1-2 km) by hot fluids circulating through rock near the earth's surface. Epithermal deposits are a major source of gold and silver, particularly in volcanic terrains. They are classified as high-sulfidation or low-sulfidation based on the chemistry of the mineralizing fluid. Nevada's Carlin Trend and many other western U.S. gold districts are epithermal systems.

Skarn

A rock formed by contact metamorphism and metasomatism where an igneous intrusion interacts with carbonate (limestone or dolostone) host rock. Skarns can host significant deposits of copper, gold, tungsten, molybdenum, zinc, and iron. Skarn deposits are common in the western U.S. and are typical targets for both lode claims and mill sites.