Provide Three Different Examples of How Minerals Can Form on Earth

Humans accept always used materials from the earth selectively. Early homo artists who painted on rock walls made their own paints from carmine and yellow pigments present in soils, pigments we now know as the minerals hematite and ochre. Countries have fought wars and trade companies battled over deposits of table salt, besides called halite, in the East Indies. Today, we build our houses out of drywall, fabricated of gypsum; we brand cement out of lime, a calcium oxide mineral; and nosotros extract aluminum from the mineral bauxite to brand aluminum foil and soda cans.

Hematite, halite, gypsum, lime, and bauxite are all minerals, naturally formed materials that take a specific chemical composition and crystal construction. Minerals are the edifice blocks of rocks, which tin can exist equanimous of one or more minerals in varying amounts. Granite, for example, contains quartz, mica, feldspar, and other minerals. Marble, on the other manus, consists entirely of the mineral calcite. Although minerals combine to form rocks, they retain their ain characteristics, much like the ingredients in a salad. You can make a salad that contains a diverseness of vegetables, like lettuce, carrots, bell peppers, and sprouts, or you can make a salad that consists solely of lettuce. In either case, the individual components are still identifiable, the way minerals can be identified inside a rock.

Fortunately, most minerals form just under certain conditions, so by identifying the minerals present in a rock, scientists can start to understand how, where, and maybe fifty-fifty when that stone formed. Agreement mineral formation also means that scientists can predict where to find economically important minerals similar bauxite, and gemstones like diamonds.

Early written report of minerals

Initially, virtually miners knew little about how minerals formed, but a lot about extracting the materials they constitute valuable. Georgius Agricola, a German physician who was much more enthusiastic about mining than medicine, documented mining practices and mineral descriptions in his book De Re Metallica, published in 1556. The championship literally translates as "On the Nature of Metals," but at that fourth dimension the word "metal" was widely used to draw whatever material from the globe. Agricola describes every aspect of mining, from how to identify minerals to 16th-century techniques for crushing ore to the uses of minerals and the diseases that they could cause (see the Classics link under the Resources tab to run across original woodcuts from De Re Metallica).

Agricola'south book remained a mining standard for virtually 2 hundred years and is considered the starting time major contribution to the science of mineralogy. Despite the comprehensive nature of the book, Agricola had little understanding of the cardinal composition of minerals – in other words, he had no fashion of knowing their chemic formulas. Though much thought had been devoted to the concept of atoms, the experiments that would let scientists to ascertain the nature of atoms, and thus the chemical limerick of minerals, were more than than 200 years away when Agricola began writing. Thus, early on on, the science of mineralogy advanced on the basis of describing the shape of minerals and their defining properties, similar hardness, instead of their atomic structure.

Comprehension Checkpoint

The classic 1556 book De Re Metallica (

Defining a mineral

The word "mineral" means something very specific to Globe scientists. By definition, a mineral:

1. Is naturally formed;
2. Is solid;
3. Is formed past inorganic processes;
4. Has a specific chemical composition; and
5. Has a characteristic crystal structure

Though each of these aspects of a mineral may seem elementary, they take important implications when considered together.

1. Naturally formed: Minerals form through natural processes, including volcanic eruptions, atmospheric precipitation of a solid out of a liquid, and weathering of pre-existing minerals. Today, scientists, engineers, and manufacturers synthesize many ceramics, plastics, and other substances with a specific chemic composition and structure, just none of these synthetic substances is considered a true mineral.

2. Solid: Liquids and gases are non considered minerals, in large part because their structure is constantly changing, which ways they practise not have a characteristic crystal structure. A true mineral must be solid.

3. Formed by inorganic processes: Any material produced through organic action – such every bit leaves, bones, peat, vanquish, or soft beast tissue – is non considered a mineral. Nigh fossils, although they were once living, have generally had their living tissues completely replaced by inorganic processes after burying; thus, they are considered to be composed of minerals as well.

four. Specific chemical composition: Most minerals exist equally chemical compounds whose compositions can be expressed using a chemic formula. The chemical formula of table salt, or halite, is NaCl, meaning each molecule of salt consists of i sodium atom (Na) and ane chlorine atom (Cl). Other common minerals have much more complicated formulas, such as muscovite (KAl₂(AlSi₃O_ten)(OH)_ii). A few minerals, such as graphite, consist of but one blazon of atom (carbon, in this case); therefore, the chemical formula for graphite is written simply as C. All minerals are defined by their chemical composition. If we tried to alter the composition of muscovite past replacing the aluminum with iron and magnesium, for instance, we would stop up with a totally new and different mineral called biotite.

On the other mitt, many minerals do incorporate impurities, and these impurities tin vary. Quartz, for case, has the chemical formula SiO₂ and mostly does non have any color in its pure course. The presence of a minute amount of titanium (Ti), however, causes the slight pink coloration present in rose quartz, as seen in Figure one. The amount of titanium relative to the amount of silicon and oxygen is on the lodge of parts per million, however, then this is considered an impurity rather than a change in the chemical composition. In other words, rose quartz is withal quartz. Similarly, the gemstone amethyst is a class of quartz that is colored pale to deep purple by the presence of the impurity iron (Fe).

Effigy ane: An instance of rose quartz, colored by trace amounts of titanium.

Information technology was not until the 1900s, 350 years afterward Agricola'south book, that scientists were able to decide the specific chemical composition of minerals. The invention of the mass spectrometer, e'er more than powerful microscopes, and the use of diffraction techniques immune the kind of highly detailed assay that caused the science of mineralogy to flourish.

5. Feature crystal structure: Nicolaus Steno, a Dutch contemporary of Isaac Newton, fabricated an of import contribution to mineralogy in 1669 when he noted that the angles between faces (or sides) of quartz crystals were constant, no affair how big the crystals were or where they had formed. Today, we know that Steno's Law of Interfacial Angles concerning the external appearance of crystals reflects a regular, internal arrangement of atoms. The angles are constant between faces on quartz crystals because every single quartz crystal is made of the aforementioned atoms: one atom of silicon for every two atoms of oxygen, written with the molecular formula SiO₂.

The chemical limerick of a mineral is reflected internally in a regular, repeating organization of atoms, called the crystal structure of the mineral. The crystal structure of halite is shown in Figure two. The internal structure (shown on the left) is reflected in a generally consequent external crystal form (shown on the right), equally noted past Steno. The cubic shape of salt crystals very clearly reflects the right-angle bonds between the Na and Cl atoms in its atomic construction (see our Chemical Bonding module).

Most importantly, this structure repeats itself. As the halite crystal is broken into smaller and smaller pieces, information technology retains its cubic structure. Have a look at a dash of table salt under a microscope and you lot volition confirm that this is the example.

Comprehension Checkpoint

Minerals tin can exist institute in nature or made in a laboratory.

The importance of crystal structure

The graphite-diamond mineral pair is an extreme example of the importance of crystal structure. These 2 very different minerals have exactly the same chemical formula (C), just the crystal construction of the two minerals is very different. In graphite, carbon atoms are bonded together along a flat plane, equally shown in Figure three. These sheets of carbon are loosely held together past weak attractive forces. However, the bonny forces between sheets can be easily broken, allowing them to slide past i some other. Thus graphite is a soft, glace mineral that is often used as a lubricant in machines (see Figure 4). When graphite is rubbed confronting another cloth, such as a piece of paper, information technology leaves a trail of small sheets that have broken free, thus it is besides used in pencils.

In diamond, by comparing, every single carbon cantlet is bonded strongly to four surrounding carbon atoms in a 3-dimensional structure (see Figure 5). This structure results in ane of the hardest natural substances on the planet (see Figure vi), a property that contributes to its value. The structure of each of these minerals is crucial to determining their concrete properties.

Chemical composition and crystal structure are the most important factors in determining the properties of a mineral, including shape, density, hardness, and color. Geologists use these properties to identify which minerals are present in rocks. Hardness and fracture characteristics tin can be easily adamant in the field with a pocket-sized magnifying lens and a hammer, assuasive for rapid identification of the mineral.

The internal diminutive structure of graphite and diamond, shown in Figures 3 and 5, explains the properties of the two minerals.

Comprehension Checkpoint

Graphite and diamond have very unlike properties because their __________ is very unlike.

Why exercise nosotros care?

Past identifying the minerals present in a given rock, geologists can begin to empathize the history of that rock. Some minerals form only when magma erupts out of a volcano and cools, others form just deep within Earth'southward crust under tremendous oestrus and pressure, and still others form but at the surface through evaporation. The basalt that erupts out of the volcanoes in Hawaii, for example, contains olivine, a mineral that forms but inside Earth's mantle at depths greater than lxx km. This tells us that the source of the magma in the Hawaiian Islands is very deep. Sediment cores from the bottom of the Mediterranean Sea contain layers of gypsum and halite, two minerals that form but when water evaporates; this discovery led geologists to the conclusion that the Mediterranean Ocean had stale up repeatedly in the past.

Identifying minerals on other planets has also led to a greater understanding of our solar system. Hematite is a mineral that forms most commonly on Earth'southward surface in the presence of water. It is, essentially, rust, and information technology forms during weathering of iron-bearing minerals. The discovery of hematite "blueberries" on Mars was function of the evidence that led geologists to conclude that in that location once was liquid water on the planet (run into the News and Events links under the Resources tab).

The written report of minerals began with mining, and we still employ our cognition of minerals to find important economic deposits. Just our understanding of mineral limerick and structure has become essential to many other areas of study as well. The ecology remediation of mines, the exploration of other planets and search for extraterrestrial life, and the written report of the geologic history on our own planet are all areas that require knowledge of minerals and their sources.

Summary

The study of minerals provides a window into the history of World and other planets in our solar system. This first module in a iii-part series describes the history of our agreement of minerals and then defines a mineral, focusing on chemical composition and construction.

Key Concepts

• Minerals have specific chemical compositions, with a feature chemical structure.

• Minerals are solids that are formed naturally through inorganic processes.

• Chemic limerick and crystal structure make up one's mind a mineral's properties, including density, shape, hardness, and color.

• Because each mineral forms under specific weather condition, examining minerals helps scientists understand the history of earth and the other planets within our solar arrangement.

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Source: https://www.visionlearning.com/en/library/Earth-Science/6/Defining-Minerals/119

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