Exploration is the process of analyzing an area of land to find mineral deposits and acquiring the rights to explore for mineral deposits on that land.

The exploration phase is divided into three areas:

  1. Discovery - conducting research, using a variety of tools, to determine the potential location of mineral deposits
  2. Online mining claim registration - marking a section of land for the purpose of claiming the sole rights to explore for minerals on that land
  3. Assessment work - performing and recording exploration work to maintain ownership of a mining claim


Discovery involves conducting research, using a variety of tools, to determine the potential location of mineral deposits.


Ontario's mineral wealth is spread unevenly across the province. Many tools are available to assist with the process of discovering areas with mineral potential. The discovery process usually involves a variety of tools which are selected based on cost, project timelines, the size of the area being explored, the type of minerals being searched for and the required level of accuracy.


The Mines and Minerals division collects data about Ontario's geology. Collected data is assembled into reports, maps and geographic information system data files which are made available through a number of applications (GeologyOntario, OGSEarth, MLAS map viewer).

John B. Gammon Geoscience Library

The Mines and Minerals division operates the John B. Gammon Geoscience Library which houses a comprehensive collection of journals, thesis, government documents, maps and reference material relating to geology and mineral exploration. The library also makes available many geoscientific journals and provides computer terminals to access the GeoRef geoscience literature database and the GeologyOntario application.

Field exploration

Field exploration involves the on-site investigation of local geology. Investigation methods may include collecting rock samples, measuring dip and alienation, analyzing rock orientation properties and measuring magnetic or electromagnetic rock properties.

Geoscience Laboratories

The Ontario Geological Survey Geoscience Laboratories, (Geo Labs) is a high-quality, full service, inorganic materials analytical facility providing analytical services in geochemistry, mineralogy, and reference materials. The Geo Labs offer these services to government, academic, exploration, mining, environmental, industrial and research organizations. The primary focus is on research grade analyses for academic institutions and government geological surveys, including the Ontario Geological Survey, the Geo Labs largest client.

For more information on the services offered by the Geoscience Laboratories, please see the current Schedule of Fees and Services (PDF).

Remote sensing

Remote sensing involves the capture of information about an area of land from a distance. Information can be captured by a variety of devices such as satellites, aircraft and airborne sensors.


The Resident Geologist Program is a network of offices located across the province which are staffed by geologists who are familiar with the geology of the surrounding region. Resident Geologist Program offices provide public access to geoscience databases and local resource material. Resident Geologist Program geologists provide geological consultation and advisory services.

The Resident Geologist Program also produces monthly reports that may include information on mining and exploration activity, property visits, mine visits, First Nations/Métis meetings, and field trips within each Resident Geologist District. Archived month end reports are available on request.

To get in touch with a geologist, contact the Resident Geologists Program or one of their local offices.

Assessment work

Understand which early exploration activities and expenses are eligible to receive assessment work credits and learn how to report assessment work in the Mining Lands Administration System (MLAS).

Assessment work refers to exploration activities that must be done on mining claims every year to maintain the right to explore for minerals and keep a claim in good standing.

Assessment work credits

The costs of assessment work are converted to assessment work credits. These credits can be assigned to a mining claim and allow you to satisfy the annual units of assessment work that must be performed or reported on a mining claim. Credits can be assigned to other claims or other assessment years if certain conditions are met.

Payment in place of assessment work

You may maintain your claim in good standing by making a monetary payment equivalent to the current year’s required assessment work. There are restrictions to how and where you can use payments in place.

Section 5 - O. Reg. 65/18 – payments in place of assessment work.

Distribution of credits

You can distribute approved credits to contiguous mining claims to maintain those claims in good standing.

Guide to distributing approved credits (PDF).

There are limits to the amount of assessment work credits that may be distributed from a reserve for a mining claim or for other mining lands to a mining claim at any given time

Section 19 - O. Reg. 65/18 – limits on the distribution of credits.


Certain types of early exploration activities constitute assessment work, and the costs related to those activities are eligible for credits. Examples of work types include:

  • grass roots prospecting
  • bedrock trenching
  • pitting
  • overburden stripping and related manual work
  • sampling
  • airborne and ground survey work
  • exploratory drilling and rehabilitation

Other costs and expenses such as certain types of labour costs, contracting fees, food/lodging, equipment rental/transportation, supplies, assays and analyses, and Indigenous consultation may also be eligible for assessment work credits. Check the assessment work regulations for a list of all eligible costs.

Grass roots prospecting

Labour costs for grass roots prospecting can be credited at 200 per cent if certain conditions are met. When submitting your assessment report in MLAS, report your actual costs (100 per cent) and, when approved, the appropriate adjustment will be reflected in accordance with section 13 of O. Reg. 65/18.

Technical standards for reporting assessment work

Assessment work must be reported to the ministry and follow technical standards applicable to the type of work that you are reporting and claiming. The technical report must include a detailed explanation of the geoscience work, maps or plans (where required), and details of the expenses claimed for the work, together with supporting receipts, invoices and other documents.

Technical standards for reporting assessment work (PDF)

Filing an assessment work report

You must submit assessment work reports through the Mining Lands Administration System (MLAS). Once your assessment report is approved, credits go into the reserves of the mining lands on which the work was performed.

You may also appoint an assessment work manager in MLAS to perform certain functions on your behalf.

Guide to filing an assessment work report

Pending distributions

If claims from your report are due in the next 90 days, consider submitting a pending distribution along with your assessment work report.

When should a pending distribution be submitted? (PDF)

If you have submitted a pending distribution with your work report, your report may be approved with changes made to where the work was reported or to the value of the work. You have 15 days from the time of notification to amend the pending distribution to keep claims in good standing.

Section 20 - O. Reg. 65/18 – Pending distributions

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