A one-ounce gold coin looks like a remarkably simple product. Its weight and purity can be checked in minutes. Producing the gold inside it, however, may have required years of exploration, thousands of tonnes of material handling and an industrial plant built specifically for one deposit.
How gold is mined depends on where the metal occurs and how tightly it is bound to other minerals. Some gold can be recovered from river gravel. Much of today’s production comes from rock containing particles too small to see. Understanding that difference reveals why a promising discovery is not necessarily a profitable mine—and why higher gold prices cannot instantly produce more bullion.
Finding a Deposit Worth Mining
A mine begins with a geological hypothesis. Geologists look for rock formations, faults and alteration patterns associated with gold, then narrow their search using mapping, surface samples and geophysical surveys. Satellite imagery can reveal structures, but it cannot establish how much recoverable gold lies underground.
That requires drilling. Cores and other samples are tested in laboratories, and the results help build a three-dimensional model of the deposit. Gold concentrations can vary sharply over short distances; a handful of impressive samples is not enough to justify construction.
Companies must then estimate resources, assess recovery methods and determine whether the project can support the necessary investment. The difference between finding mineralisation and defining an economic reserve matters enormously. Even after a discovery, engineers need to plan power and water supplies, access roads, waste facilities and mine closure.
According to the World Gold Council, moving from discovery to production typically takes 10–20 years, although individual projects vary considerably. Many prospects never get that far. The types of gold deposits also influence how difficult exploration and extraction will be.
Choosing How to Extract the Ore
Once a project is approved and built, miners have to reach the gold-bearing material. The choice is chiefly a question of geology, depth, rock conditions and economics.
An open-pit mine removes overlying rock to expose deposits accessible from the surface. Terraced benches allow drills, loaders and haul trucks to work at scale. The method can move huge volumes efficiently, but excavating waste rock adds cost and changes the landscape.
An underground mine uses shafts or inclined tunnels to reach deeper deposits. Crews work with specialised machines, ground support, ventilation and sometimes cooling systems. Underground operations may move less ore than a large open pit, yet target richer sections to offset higher extraction costs.
Placer mining is different again: it separates naturally concentrated gold particles from sand or gravel, sometimes using gravity-based equipment. Today’s industrial operations are far removed from the gold pans of historical rushes, but the underlying separation principle survives.
The comparison in open-pit versus underground gold mining explains why two deposits containing the same metal can require completely different mine designs.
Why Ore Grade and Recovery Matter
The most surprising fact about many gold mines is how little gold their ore contains. Ore grade is usually expressed in grams per metric tonne (g/t). At 2 g/t, one tonne of rock contains just two grams of gold before processing losses.
Suppose a plant achieves a 90% recovery rate on that ore. It produces approximately 1.8 grams per tonne processed. To recover one troy ounce—31.1 grams—it would need to process roughly 17 tonnes of ore. This is an illustrative calculation, not a universal mining average; it excludes additional waste rock stripped away to reach the deposit.
| Measure | Illustrative value | What it means |
|---|---|---|
| Ore grade | 2 g/t | Gold contained in each tonne of ore |
| Processing recovery | 90% | Share of contained gold actually recovered |
| Recovered gold | 1.8 g/t | Gold obtained per tonne processed |
| Ore needed for 1 troy ounce | About 17.3 tonnes | Before allowing for mining waste and other losses |
Grade alone does not determine whether a mine makes money. Recovery, deposit size, energy prices, transport, stripping costs and the gold price all matter. Some low-grade open pits are profitable because they process enormous volumes; a higher-grade underground deposit can still be uneconomic if access is exceptionally difficult. The gold grades guide explores these trade-offs in more detail.
How Processing Plants Recover Gold
Once ore reaches the processing plant, large crushers and grinding mills break it down. The aim is not merely to make smaller rocks. It is to liberate gold particles from the minerals enclosing them so a recovery process can reach the metal.
There is no universal flowsheet. Depending on the ore, plants may use a combination of techniques:
- Gravity concentration separates relatively coarse, dense gold particles from lighter material.
- Flotation concentrates certain gold-bearing sulfide minerals for further treatment.
- Chemical leaching, commonly involving carefully managed cyanide solutions, can recover gold that cannot be separated efficiently by gravity alone.
Some ores are refractory: the gold is trapped inside minerals and requires additional treatment before recovery. Two mines with similar grades may therefore have very different operating costs and recovery rates. That is why understanding gold ore is essential to understanding mine economics.
After gold has been recovered from a solution or concentrate, further processing produces a metal alloy. Meanwhile, the remaining material—tailings—must be managed. Chemical handling, water use and waste containment are fundamental engineering and environmental responsibilities, not minor details at the end of the process.
From Doré Bars to Investment-Grade Gold
Many mines pour their recovered metal into doré bars, which contain gold mixed with silver and other metals. Their composition varies by operation. A doré bar may look like a finished gold bar, but it is not yet the high-purity product usually sold to investors.
Specialist refineries assay the incoming material and remove impurities. Refining can involve different chemical and electrochemical methods before the resulting gold is cast or supplied for minting.
Purity requirements depend on the product and market. Retail investment bars commonly contain 99.99% gold, while the London Bullion Market Association’s large Good Delivery bars require a minimum fineness of 99.5%, not 99.99%. A bar’s recognised standard, stated fine-gold content and refiner credentials matter as much as its appearance.
From there, gold can become investment bars, bullion coins, jewellery or industrial components. A useful distinction for buyers is that the quoted gold price does not include every dealer premium, fabrication charge or resale spread. The guide to buying physical gold and silver covers those practical differences.
Mining Costs, Environmental Risks and Mine Closure
The cost of mining gold goes far beyond excavators. Its costs may include drilling, skilled labour, diesel or electricity, water treatment, replacement equipment, security and ongoing exploration. A remote site may also need roads, a power plant or accommodation before production begins.
One cost rarely visible in a photograph of a gold bar is the obligation to manage the site responsibly. Tailings storage, water quality, worker safety and community impacts require monitoring throughout the mine’s life. Where cyanide is used, controls are particularly important; the International Cyanide Management Code provides a voluntary audited framework for handling it.
When mining ends, facilities must be decommissioned and disturbed land rehabilitated where possible. Monitoring may continue long after the last ore truck leaves. These obligations help explain why the future of gold mining depends on permitting, capital and environmental performance as well as new discoveries.
Why New Gold Supply Cannot Expand Overnight
A miner can respond to higher prices by extending an existing operation or processing material that was previously uneconomic. Building an entirely new mine is another matter. A deposit must survive technical studies, financing, approvals and years of construction before producing a saleable ounce.
The World Gold Council estimates that worldwide mine production reached approximately 3,672 tonnes in 2025, yet even strong prices have not produced an immediate surge in output. That slow response is part of gold’s supply story, although it should not be mistaken for proof that the world is about to run out of mineable gold.
The Gold & Silver Production and Reserves Map shows how mine output and identified reserves are distributed geographically. Nor does every ounce sold today come from a mine. Recycled gold from jewellery and other products provides an additional source of supply, generally able to respond faster to changing prices.
For investors holding a finished coin or bar, the production chain is worth understanding. It explains the metal’s scarcity, the difficulty of increasing mine output and the care required to turn rock into trusted bullion. Mining cannot guarantee a rising gold price. It does explain why supplying new physical gold is never as simple as deciding to make more.
Frequently Asked Questions
How is gold mined?
Gold mining begins with geological exploration and drilling to identify economically viable deposits. Companies then extract gold-bearing ore using open-pit or underground mining methods. The ore is crushed, processed to recover the gold, and typically sent for further refining before becoming investment-grade bullion.
Where is gold found, and what is gold ore?
Gold occurs in geological deposits within rock formations and in sediments such as river gravel. Gold ore is material containing enough recoverable gold to justify extraction under prevailing economic conditions. Many deposits contain only a few grams of gold per tonne, while others are too costly to mine profitably.
How is gold separated from rock?
Gold-bearing ore is usually crushed and ground to release gold particles from surrounding minerals. Processing plants may use gravity separation, flotation, or chemical leaching to recover the metal. The most suitable method depends on the ore’s composition, particle size, and how the gold occurs within the rock.
What is a gold doré bar?
A doré bar is a partially refined metal bar typically produced at a gold mine. It contains gold mixed with varying amounts of silver and other impurities. Doré bars are transported to specialized refineries, where their metal content is measured and the gold is purified for commercial or investment use.
How is gold refined into investment-grade bullion?
Refineries use chemical and electrochemical processes to separate gold from silver and other impurities. Many retail investment bars contain 99.99% pure gold, although purity requirements vary by product. London Good Delivery gold bars, for example, must meet a minimum fineness of 99.5%.
How long does it take to develop a gold mine?
Developing a new gold mine commonly takes 10 to 20 years from initial discovery to production, although timelines vary considerably. Exploration, resource evaluation, environmental assessments, permitting, financing, and construction can each require several years. Many discovered deposits never become operating mines.
Why is gold mining so expensive?
Gold mining requires substantial investment in exploration, equipment, infrastructure, skilled workers, and ore processing. Low-grade deposits may require millions of tonnes of material to be handled each year. Energy, water management, environmental protection, and eventual mine closure add further costs throughout a project’s life.
Explore More Gold Mining Guides
Types of Gold Deposits | Open-Pit vs Underground Gold Mining | Largest Gold Mines in the World | Largest Gold Producing Countries | Gold Recycling Explained | The Cost of Mining Gold | Future of Gold Mining
