Formation and classification of placer gold deposits

Erosion and Weathering

Gold is released from native gold-bearing rocks through weathering and erosion processes, breaking down the host rock and releasing gold particles.

Waterway transportation

Gold particles are transported by water, usually a river or stream. Currents, especially during high-energy periods such as floods, can carry gold particles over great distances.

Deposition

When water velocity decreases, such as in a river bed or sedimentary basin, gold particles settle and accumulate due to their higher density. Gold deposition in these areas resulted in the formation of placer gold deposits.

Classification of placer gold deposits

Placer gold deposits are widely distributed and of various types. They can generally be divided into the following types:

Alluvial placer gold deposits: These are the most common type of placer gold deposits. Gold particles are deposited by water in river beds, floodplains and deltas. Alluvial placers, such as rivers, benches, and floodplains, can be further classified based on location.

Eluvial Placer Deposits: Gold is concentrated above the source rock due to weathering and decomposition. Placer deposits of this type are commonly found on hillsides and slopes.

Beach sediments: Gold accumulates on beaches due to the action of waves and tides. Gold's high density allows it to precipitate from lighter beach sand.

Glacial placers: These deposits are the result of gold being transported by glaciers. As glaciers move across the surface, they can absorb and transport gold particles, depositing them as the glaciers melt.

Residual Placer: Gold concentrated in soil and weathered rock material over the bedrock of its source. This type of placer deposit often occurs in heavily weathered areas.

Bench Deposits: Gold accumulates on raised platforms or benches along river banks, usually formed during changes in the river's course.

Stream deposits: Gold is deposited in active stream channels, often associated with meandering streams and bedrock exposures.

Depending on the main types of minerals contained in the deposits, placer gold deposits can be divided into:

Mixed placer deposits: Contain a variety of minerals and metals, such as gold, silver, tin, iron, etc., mixed to form placer gold.

Placer gold deposits: Ore sands containing mainly gold particles. This is the most common type of placer gold deposit and is sometimes called a placer gold deposit.

Magnetite Sand Deposit: Contains magnetite and gold sand. Since magnetite is magnetic, it can be separated by magnetic separation and other methods.

Tin sand deposit: contains tin ore and gold sand, among which the tin ore may be cassiterite, cassiterite, etc.

Uranium placer deposit: Contains uranium ore and gold sand. This type of deposit is common in areas containing uranium ore.

Ilmenite sand deposit: contains ilmenite ore and gold sand, of which ilmenite ore is mainly composed of sulfite and ilmenite.

Heavy mineral sand deposits: contain denser minerals, such as gold, magnetite, tin ore, etc. These minerals will be enriched due to density differences during the deposition process.

The classification of placer gold deposits helps geologists and miners understand the geological background and characteristics of the deposits and helps develop effective extraction and processing methods. Each type of placer mine may require different mining techniques and equipment