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Liberia has some of the largest iron ore reserves in Africa, with iron content of 30% to 67%, in banded iron formations from the Precambrian. The high grade ores, with more than 60% are primarily hematite, while lower grade ores with 30 to 40% iron are generally magnetite. Liberia also has medium-grade deposits of mixed hematite and magnetite.
Speaking broadly, mineral color points out the specific gravity of the mineral, as minerals that are lighter in color tend to be less dense. Darker minerals typically tend to contain more of relatively heavy elements, notably iron, magnesium, and calcium. [2] The temperature of crystallization affects what the color index of rocks tends to be. [10]
In mineralogy, an inclusion is any material trapped inside a mineral during its formation. In gemology , it is an object enclosed within a gemstone or reaching its surface from the interior. [ 1 ] According to James Hutton 's law of inclusions, fragments included in a host rock are older than the host rock itself.
The timing of mineral crystallization can be used to categorize diamond inclusions into three types: protogenetic, syngenetic, and epigenetic inclusions. [14] Minerals in the protogenetic inclusions were crystallized earlier than the diamond formation. The host diamond encapsulated pre-existing minerals during its crystallization.
A mafic mineral or rock is a silicate mineral or igneous rock rich in magnesium and iron. Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite. Common mafic rocks include basalt, diabase and gabbro. Mafic rocks often also contain calcium-rich varieties of plagioclase ...
The mining industry of Liberia has witnessed a revival after the civil war which ended in 2003. [1] Gold, diamonds, and iron ore form the core minerals of the mining sector with a new Mineral Development Policy and Mining Code being put in place to attract foreign investments. [ 2 ]
Heavy minerals (dark) in a quartz beach sand (Chennai, India). Heavy mineral sands are a class of ore deposit which is an important source of zirconium , titanium , thorium , tungsten , rare-earth elements , the industrial minerals diamond , sapphire , garnet , and occasionally precious metals or gemstones .
Dark soil color imparted by organic matter in Illinois, US. Dark brown or black colors typically indicate that the soil has a high organic matter content. [4] Organic matter coats mineral soil particles, which masks or darkens the natural mineral colors. [1] Sodium content also influences the depth of organic matter and therefore the soil color.