Many people hunt for gold rocks for a myriad of reasons. T
he monetary and ornamental value of gold minerals surpasses others.
The process of the rocks’ formation affects the location of the stones.
In this article, we shall learn about the characteristics and chemical components of the rocks containing gold.
5 Rocks That Contain Gold
1. Sedimentary Rocks
Sedimentary rocks result from igneous and metamorphic rocks parting their gold into other stones.
The process of parting can be due to hydrothermal, weathering, or erosion.
When igneous and metamorphic rocks weather or erode, the contents are deposited into rivers or sediments in lakes.
The characteristics of sedimentary rocks include;
- Known to cover 75% of the earth’s area
- Non-Crystalline in nature
- It contains many layers due to sediment deposition.
- Can exist in between some layers of plant and animal remains
The chemical components of the rocks are quartz at 65% and feldspar at 10 to 15%.
Other minor features include; carbonate minerals, hematite, and calcite.
The rocks are found on the earth’s surface everywhere in the world.
The likeliest places are water sources where erosion can occur, including riverbeds, coasts, and ponds.
2. Igneous Rocks
The rocks are primarily metal-bearing ornamental rocks.
In some cases, gold particles in the rocks are visible to the eye.
The cooling of molten rocks leads to the formation of igneous rocks.
Magma and lava ( released during volcanic eruptions) cool, forming igneous rocks.
The texture of the rocks can be:
- Aphanitic, fine-grained.
- Phaneritic, coarse-grained.
- Pegmatitic, very coarse-grained.
- Porphyritic, large, and fine-grained crystals.
- Vesicular, rocks with vesicles.
- Pyroclastic, angular, fragmented grains are released during the eruption.
- Glassy, non-ordered solid formed as lava cools quickly.
The critical properties of the rocks include;
- Don’t include fossil deposits.
- Consists of multiple mineral deposits.
- It can be coarse or glassy.
- Don’t react with acids.
Patched forms and different sizes of the rock contain mineral deposits.
The igneous rocks can be either intrusive or extrusive.
In intrusive rocks, crystallization occurs below the earth’s surface, and extrusive stones erupt onto the surface.
Examples of rocks are; granite, basalt, and pumice.
The chemical composition of the rock consists of felsic, magic, ultramafic and intermediate
3. Metamorphic Rocks
When sedimentary and igneous stones don’t reach the melting point, it results in metamorphic rocks.
The change occurs due to high amounts of heat, hot fluids, high pressure, or a combination of the listed factors.
The gold quantities in the rocks aren’t visible.
The amount of gold in metamorphic rocks is low, usually less than 5 PPB, making many people not pursue gold extraction in these rocks.
The common types are phyllite, gneiss, marble, schist, and quartzite.
Prominent characteristics of the rocks are:
- Higher density and lower porosity compared to other rocks formed due to metamorphism
- Coarser than igneous and sedimentary rocks in texture
- Steady at intense temperatures and pressures
The chemical compositions of the rocks are hornblende, plagioclase, and biotite.
Mountain ranges like the Himalayas, the Alps, and the Rocky Mountains are some places where we can find rock.
Generally, within the earth’s crust or tectonic plates.
4. Granite Rock
Gold-bearing veins exist in granite rocks.
Volcanic rocks and adjacent granite birthed gold and other mineral veins through intrusion.
The ornamental stones are pink-gray and belong to the plutonic group of stones.
Also, it has a massive and confining structure.
Granite rocks contain three major minerals; quartz, feldspar, and mica.
Other minerals include; orthoclase, biotite, plagioclase, and Muscovite.
The main chemical compositions of granite rocks are silica at 72.04% and alumina at 14.42%.
Smaller compositions include areas with deeply eroded earth’s crust contain granite rocks.
Primarily found in small, stonelike masses or batholiths in orogenic mountain regions.
5. Quartz Rocks
Silicon and oxygen from the earth’s crust form quartz rocks.
The rock contains other rock classes like igneous, metamorphic, and sedimentary and mineral environments.
The chemical components of quartz rocks are;
- Only silicon atoms and oxygen atoms with the formula SiO2.
- The rock contains a continuous tetrahedral framework, with 4 oxygen atoms surrounding one silicon atom particle.
Physical properties include;
- It can be found in different colors, though when pure, it is colorless or white.
- Impurities lead to color change into pink, brown, purple, black, gray, green, blue, yellow, orange, red, or brown.
- The rocks contain vitreous luster, thus interacting with light just like glass.
- Relatively complex and stable to harsh chemicals and high temperatures. Only strong acids like hydrofluoric acid dissolve the rock.
The United States, Madagascar, Japan, the Alps, and Minas Gerais in Brazil are some areas where we can find quartz rocks.
We can find gold in sedimentary, igneous, and quartz rocks.
Sedimentary rocks provide the highest gold quantities compared to others.
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