File Name: physical and chemical properties of quartz .zip
Geologists have recently determined that the minerals goethite and hematite exist in abundance on Mars, sure signs of the presence of water see Figure 1 for a picture. None of those geologists have been to Mars, of course, but the unmanned rovers Spirit and Opportunity have.
Covid has significantly affected our fundraising. Please help! Learning Center What is a mineral?
All rocks except obsidian and coal are made of minerals. Obsidian is a volcanic rock made of glass and coal is made of organic carbon. Most rocks contain several minerals in a mixture characteristic of the particular rock type. When identifying a rock you must first identify the individual minerals that make up that rock. Minerals are naturally occurring, inorganic solids with a definite chemical composition and a crystal lattice structure.
Properties of Minerals
All rocks except obsidian and coal are made of minerals. Obsidian is a volcanic rock made of glass and coal is made of organic carbon. Most rocks contain several minerals in a mixture characteristic of the particular rock type. When identifying a rock you must first identify the individual minerals that make up that rock. Minerals are naturally occurring, inorganic solids with a definite chemical composition and a crystal lattice structure. Together, the chemical formula the types and proportions of the chemical elements and the crystal lattice the geometry of how the atoms are arranged and bonded together determine the physical properties of minerals.
The chemical formula and crystal lattice of a mineral can only be determined in a laboratory, but by examining a mineral and determining several of its physical properties, you can identify the mineral. First, you need to become familiar with the physical properties of minerals and how to recognize them.
Minerals can be identified by their physical characteristics. The physical properties of minerals are related to their chemical composition and bonding. Color is readily observable and certainly obvious, but it is usually less reliable than other physical properties.
Figure 1. This mineral has shiny, gold, cubic crystals with striations, so it is pyrite. Mineralogists are scientists who study minerals. One of the things mineralogists must do is identify and categorize minerals. While a mineralogist might use a high-powered microscope to identify some minerals, most are recognizable using physical properties. What is its shape? Are the individual crystals shiny or dull? Are there lines striations running across the minerals?
Diamonds are popular gemstones because the way they reflect light makes them very sparkly. Turquoise is prized for its striking greenish-blue color. Notice that specific terms are being used to describe the appearance of minerals. Figure 2. This mineral is shiny, very soft, heavy, and gold in color, and is actually gold. Color is often useful, but should not be relied upon. Different minerals may be the same color.
Real gold, as seen in figure 2, is very similar in color to the pyrite in figure 1. Additionally, Some minerals come in many different colors. Quartz, for example, may be clear, white, gray, brown, yellow, pink, red, or orange. So color can help, but do not rely on color as the determining property. A tiny amount of iron makes the quartz purple. Many minerals are colored by chemical impurities.
Figure 3. Purple quartz, known as amethyst, and clear quartz are the same mineral despite the different colors. Mineralogists have special terms to describe luster. One simple way to classify luster is based on whether the mineral is metallic or non-metallic. Minerals that are opaque and shiny, such as pyrite, have a metallic luster. Minerals such as quartz have a non-metallic luster.
Luster is how the surface of a mineral reflects light. It is not the same thing as color, so it crucial to distinguish luster from color. Standard names for luster include metallic, glassy, pearly, silky, greasy, and dull. It is often useful to first determine if a mineral has a metallic luster. A metallic luster means shiny like polished metal.
For example cleaned polished pieces of chrome, steel, titanium, copper, and brass all exhibit metallic luster as do many other minerals. Of the nonmetallic lusters, glassy is the most common and means the surface of the mineral reflects light like glass. Pearly luster is important in identifying the feldspars, which are the most common type of mineral. Pearly luster refers to a subtle irridescence or color play in the reflected light, same way pearls reflect light.
Silky means relecting light with a silk-like sheen. Greasy luster looks similar to the luster of solidified bacon grease. Minerals with dull luster reflect very little light.
Identifying luster takes a little practice. Remember to distinguish luster from color. Figure 4. Figure 5. The streak of hematite across an unglazed porcelain plate is red-brown.
Streak is a more reliable property than color because streak does not vary. Minerals that are the same color may have a different colored streak. Many minerals, such as the quartz in the figure 3, do not have streak. To check streak, scrape the mineral across an unglazed porcelain plate Figure 5. Yellow-gold pyrite has a blackish streak, another indicator that pyrite is not gold, which has a golden yellow streak. Mass is a measure of the amount of matter in an object. The amount of space an object takes up is described by its volume.
The density of an object depends on its mass and its volume. For example, the water in a drinking glass has the same density as the water in the same volume of a swimming pool. The specific gravity of a substance compares its density to that of water.
Substances that are more dense have higher specific gravity. Hardness is the strength with which a mineral resists its surface being scraped or punctured. In working with hand samples without specialized tools, mineral hardness is specified by the Mohs hardness scale. The Mohs hardness scale is based 10 reference minerals, from talc the softest Mohs hardness of 1 , to diamond the hardest Mohs hardness of It is a relative, or nonlinear, scale.
A hardness of 2. To compare the hardness of two minerals see which mineral scratches the surface of the other. With a Mohs scale, anyone can test an unknown mineral for its hardness. Imagine you have an unknown mineral. Note that no other mineral can scratch diamond.
Breaking a mineral breaks its chemical bonds. Since some bonds are weaker than other bonds, each type of mineral is likely to break where the bonds between the atoms are weaker. For that reason, minerals break apart in characteristic ways. Figure 6. A close-up view of sodium chloride in a water bubble aboard the International Space Station. Cleavage is the tendency of a mineral to break along certain planes to make smooth surfaces. Halite breaks between layers of sodium and chlorine to form cubes with smooth surfaces figure 6.
A mineral that naturally breaks into perfectly flat surfaces is exhibiting cleavage. Not all minerals have cleavage. A cleavage represents a direction of weakness in the crystal lattice. Cleavage surfaces can be distinguished by how they consistently reflect light, as if polished, smooth, and even. The cleavage properties of a mineral are described in terms of the number of cleavages and, if more than one cleavage, the angles between the cleavages.
The number of cleavages is the number or directions in which the mineral cleaves. A mineral may exhibit cleavage surfaces parallel to each other. Those represent a single cleavage because the surfaces are all oriented in the same diretion. The possible number of cleavages a mineral may have are 1,2,3,4, or 6.
To see mineral cleavage, hold the mineral up beneath a strong light and move it around, move it around some more, to see how the different sides reflect light. A cleavage direction will show up as a smooth, shiny, evenly bright sheen of light reflected by one set of parallel surfaces on the mineral.
One reason gemstones are beautiful is that the cleavage planes make an attractive crystal shape with smooth faces. Fracture is a break in a mineral that is not along a cleavage plane. Fracture is not always the same in the same mineral because fracture is not determined by the structure of the mineral. Minerals may have characteristic fractures figure 9. Metals usually fracture into jagged edges. If a mineral splinters like wood, it may be fibrous.
Properties of Minerals
These metrics are regularly updated to reflect usage leading up to the last few days. Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts. General trends of decreasing solubility of acid-cleaned radiolarians with increasing age suggest that cherts and porcelanites recrystallized cristobalite and quartz are presently forming. The thermodynamic properties of biogenic silica are between those of silica gel and cristobalite. The specific surface area of biogenic silica assemblages has decreased by two orders of magnitude in the last 40 million years. Heterogeneous solution rate constants for pure substances yield valuable information regarding the free energy of activation of solution processes.
For comprehensive utilization of powder quartz, a detailed mineralogical analysis is needed. In this paper, the minerals collected from a powder quartz deposit in Yunnan Province and its purification products were characterized by X-ray diffraction XRD , chemical composition, and scanning electron microscopy SEM analyses. It had narrow particle size distribution with whiteness of The impurity minerals kaolinite and illite existed in the forms of aggregates with quartz or inclusions in quartz particles and could be easily removed. The mineralogical characterization suggested that the powder quartz deposit was formed by long-term weathering of feldspathic or felsic rocks, possible of pegmatitic origin. Handling of fine, usually submicrometer-sized, powders in large quantities requires a high degree of process control to achieve the desired microstructural characteristics, e.
Quartz is one of the most famous minerals on the earth. It occurs in essentially all mineral environments, and is the crucial constituent of many rocks. It is likewise the maximum varied of all minerals, taking place in all distinct bureaucracy, habits, and colorings.
Quartz crystals: Herkimer "Diamond" quartz crystals. A clear, "rock crystal" variety of quartz. Quartz is a chemical compound consisting of one part silicon and two parts oxygen.
Mineralogical Magazine ;; 73 4 : — Quartz is one of the most abundant minerals in the Earth's crust and the most important silica mineral, occurring in large amounts in igneous, metamorphic and sedimentary rocks. The mineral is widely used as a raw material in several industrial applications.
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Reading: Physical Characteristics of Minerals
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До апельсиновых деревьев не меньше ста метров. Никаких шансов. Боль в боку усилилась. Сверху слышался гулкий звук шагов, спешащих вниз по лестнице. Беккер закрыл глаза, стиснул зубы и подтянулся.
Стало трудно дышать. Сьюзан бессильно прижалась к двери, за которой, всего в нескольких сантиметрах от нее, работала вентиляция, и упала, задыхаясь и судорожно хватая ртом воздух. Сьюзан закрыла глаза, но ее снова вывел из забытья голос Дэвида.
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Да-да. - Сеньор, у нас нет рыжеволосых. У нас только настоящие андалузские красавицы. - Рыжие волосы, - повторил Беккер, понимая, как глупо выглядит.
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