Basic Geology Principles
Minerals and rocks: Those who are in the mining industry, investors and all the people who are employed in it, do not have the obligation of knowing as much as a geologist knows concerning the Earth. But these people should know the basics, to say the least, of geology and should have some understanding of the more common minerals and rocks.
A small amount of knowledge of geology can go a very long way for the investors who place their funds in working the ground for minerals and rocks. An investor could some day benefit from the fact of knowing, for instance, that faulting can play havoc with an orebody or that mineral deposits which are at low temperatures, most silver orebodies, vary rapidly with depth.
The science of the Earth, Geology, is divided into many braches. In this article we will be dealing specifically with the ones that are directly bearing on finding mines, starting with a discussion on how deposits of minerals form in the crust of the Earth.
The five elements which are most abundant on the Earth’s crust are calcium, iron, aluminum, silicon and oxygen. These elements join together in chemical compounds to create solid crystalline substances which are known as minerals.
The amounts of different kinds of minerals are in the thousands, each one of them has a definite crystalline structure and chemical composition. For example, Oxygen, silicon, aluminum and potasium combine in a definite ratio to produce the common rock-forming mineral orthoclase. Sulphur and iron are combined in a definite ratio to create the yellowish mineral pyrite.
The common rock-forming minerals, as is the case of orthoclase, are for the most part silicates – in other words, they are minerals which contain oxygen and silicon. Oxides are minerals with elements which are bonded to oxygen, whereas sulphides are minerals with elements which are bonded to sulphur. The fourth important mineral group is the carbonates; this is the bond between oxygen and carbon which are bonded with other elements.
You might ask yourself what the difference is between a rock and a mineral, a rock is only a solid mass of grains of minerals. A rock is classified according to the kinds and proportions of minerals it contains
What we call mineral deposits is where minerals are concentrated in sufficient quantity, the bodies or zones in which they are found. Mineralization becomes ore when the minerals are present in enough tonnage, or quantity, and appropriate grade, or quality to be recovered with profits.
We most of the time mine these deposits to produce metals or other commodities like coal and uranium. The vast majority of people can very easily identify metals which are commonly used such as tin, aluminum, zinc, copper, silver and gold. These metals have a distinctive lustre, conduct electricity and heat, and are malleable under pressure and heat
A metallic material consisting of two or more elements is the alloy, it is homogenous in its external appearance, and is combined in such a way that they cannot be readily separated or divided by physical means. More often we use alloys than pure metals because they most of the time have properties which are different than the ones of the metals from which they are made. For instance, if we combine copper and tin together, we create an alloy which is tougher and harder than any of these two metals in their natural and pure form. Bronze is the alloy, and when it was discovered it marked the era of civilization which is known as the Bronze Age. Nowadays, alloys are used in the advanced technologies of energy, electronics and even aerospace.
We often categorize metals into groups so as to show some common uses or similar properties. Gold, silver and platinum are considered noble or precious metals, while copper, lead and zinc are mainly considered base metals due to the fact that they are of lower value.
Metals which have a strong chemical affinity to iron go by the name of ferrous metals, these metals most of the time are used in the making of steel. Molybdenum, manganese, cobalt and chromium are most of the time included in this group; this group is sometimes called ferroalloy metals because their most important use is to improve the properties of steel
The group of non-ferrous metals include zinc, tin, nickel, magnesium, lead, copper, and aluminum, due to the fact that their most important uses are not in the making of steel (some kind of overlap is made here with the base metals).
Titanium, aluminum, magnesium and berrylium are placed in the group of light metals and are valued for their combination of strength and lightness. Ruthenium, tungsten and niobium are placed in the group of refractory metals; they have high melting points and can resist high temperatures. Cesium, strontium and lithium are placed in the group of reactive metals; these metals are less stable because they react with oxygen very easily. Plutonium, uranium, throrium and radium are included in the group of radioactive or nuclear metals; these metals are often used for the purpose of generating power.
Selenium, arsenic and silicon are placed in the group called semi-metals or metalloids, these metals possess a combination of metallic and non-metallic attributes. Another group which includes zirconium, yttrium, scandium and fifteen other elements collectively termed the lanthanides are named rare-earth metals. These metals are so categorized not because they are rare in the Earth’s crust, but due to the fact that they are so difficult to extract from the Earth.
Minerals and metals are a natural part of our environment, the task that has worried mankind since the beginning of civilization has been finding economic concentrations of them in the earth’s crust.