Mineral properties change hands constantly, and the process is less mysterious than it appears from outside. What follows is a plain-language walk through the questions a buyer needs answered before committing to a Mexican mining concession — and why each one matters.
- Title status and expiry
In Mexico, mineral rights are held through concessions granted by the federal government. A concession is not ownership of land; it is the exclusive right to explore for and extract minerals within a defined polygon. The first thing to verify is that the concession is current, that fees have been paid, that required assessment work has been reported, and that no liens or encumbrances are registered against it.
Expiry date deserves particular attention. Concessions granted before the 2023 mining reform carry fifty-year terms. Those granted after do not. A buyer with a long development timeline should confirm exactly how much runway the title provides. This is one reason mining concessions for sale in Mexico with pre-reform titles are examined more closely than the reform coverage would suggest — the remaining term is a real component of value.
Verify the expiry against the actual title documents held at the mining registry. Do not accept a summary figure from a seller’s presentation, however reputable the seller. Arithmetic derived from a stated grant year and a stated term is not the same as a document.
- Surface rights versus mineral rights
A concession grants mineral rights. It does not grant the right to walk onto the land. Surface access in Mexico is negotiated separately with whoever holds it — a private owner, an ejido (a communal landholding), or a combination. A concession with no surface agreement is a concession you cannot reach. Establish what agreements exist, what they cost, when they expire, and whether the counterparty has any history of dispute.
- Environmental and community standing
Ask what permits are held, what obligations attach to them, and whether any remediation liability from prior activity transfers with the property. Ask separately about community relations, which are not a permit but will determine whether a project proceeds. A property with recent operating history offers useful evidence here: if material moved and was shipped, access and local relations functioned at least once.
- Historical data and its limits
Most properties come with a file of prior work — drill logs, assay results, sometimes a resource estimate. Treat all of it as unverified until proven otherwise. Ask three questions. Who generated it and what were their credentials? Has any independent party reviewed it? Have the assays been re-run at an accredited laboratory?
The third question matters most. A check-assay programme takes original sample material to an accredited lab — ISO 17025 is the relevant standard — and re-analyses it. A high reproduction rate means the original numbers can be provisionally trusted. A poor one means the entire dataset is worthless regardless of how attractive the grades look.
Be equally clear on reporting standards. A historical estimate is not a mineral resource. Under NI 43-101, the Canadian standard, an estimate cannot be treated as current unless a qualified person has done the work to classify it. Sellers may legitimately disclose historical estimates with that qualification attached; buyers should never model from them.
- Metallurgy
Grade tells you what is in the rock. Metallurgy tells you what you can get out. Bottle-roll cyanidation is a standard early test, and recoveries in the 90 percent range indicate conventional processing will work. Low or erratic recoveries signal refractory mineralisation, which means a more complex and far more expensive plant. This is a question that must be answered before valuation, not after.
A worked example
The Charay Project in the San Blas district of Sinaloa illustrates how these boxes get ticked. Three contiguous concessions — San Luis 190743, Charay 219738, Charay 2 222491 — covering 380 hectares under pre-reform fifty-year titles expiring between 2041 and 2054. A 2010 independent qualified-person recompilation covering 27 core holes and 1,576 metres. Check assays at an ISO 17025 laboratory reproducing originals at 91 percent. Bottle-roll recoveries of 90 to 94 percent. And a 2015 campaign that processed 15,430 tonnes for 3,668 troy ounces of gold and 24,550 troy ounces of silver, four months from agreement to first shipment.
A historical estimate also exists and is disclosed as non-compliant with NI 43-101 and not to be relied upon — which is exactly how a historical estimate should be presented.
The checklist does not tell you whether a property is worth buying. It tells you what you are buying, which is the prerequisite.