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Mineral characteristic practice - Contenido educativo
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Avery Masters explica en inglés las propiedades (brillo, raya, dureza ...) de los minerales que los alumnos trabajarón previamente en el laboratorio.
Avery Masters explain the main characteristic of some minerals.
Avery Masters explain the main characteristic of some minerals.
Welcome to Practice 12. We're going to look at the physical properties of minerals and
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how they're found both in the natural world and their composition. So, the minerals are
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here. Minerals are naturally occurring inorganic substances, which form rocks of the Earth's
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crust. The physical properties of minerals reflect their chemistry and internal structure
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and provide keys to their identification. Some chemical properties may be determined,
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such as testing for a reaction with hydrochloric acid or determining the density and specific
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heat of the mineral. With knowledge of both these characteristics, identification of minerals
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becomes much easier. The most common rock-forming minerals can be identified by some key properties.
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In today's lab, you will test minerals for some of these key characteristics. So, we
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will look at color. We'll make a streak test. We'll look at luster, cleavage, hardness,
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and we will make, on certain minerals, a chemical test, which we will place a drop of hydrochloric
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acid and see whether or not the chemical reacts with bubbles to the mineral at that time.
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In this lab, we're going to use minerals. We're going to use a porcelain tile that's
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white for the streak test. We're going to use glass and a copper wire and our own fingernail
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to test hardness of the minerals and whether or not they can be scratched based on a scale
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with our fingernail, with copper wire, or with glass, which will tell us about how hard they
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are. The next mineral we're going to look at is a very common mineral. This is graphite,
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and we put it in pencils. We use it all the time, and it's a mineral we find often in nature. It is
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quite common and quite useful. So, we're going to look at five important characteristics. First of
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all, we look at the luster. Luster is whether or not it is dull, metallic, shiny, and this is a
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dull mineral. It is not shiny. It is not crystal. The color is gray, and when we make a streak test
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with graphite, placing it on the porcelain tile, we can see a streak of black. So, we know that
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it is the streak test would be black, and for hardness, the first test we make is of a human
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fingernail, and we can see that a human fingernail can scratch graphite. So, we know that it is very
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soft, and on the number scale of very soft to very hard, it is a one or two rating of softness.
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Finally, we test for density. So, we feel for weight and density, whether or not it's heavy
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or light, and this mineral is light. So, that is the physical testing of the mineral graphite. This mineral is
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called galena, and again, we're going to do the physical testing. So, first of all, we look very
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simply at the mineral. Its luster is not dull like the graphite. Instead, it is metallic. Its color
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is black, white, brown, but predominantly black, and when we use it for the streak test on our
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porcelain tile, we can see that it leaves a black streak. In terms of hardness, if at first the
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fingernail has no effect, the copper wire is equally incapable of scratching, and then with the glass,
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we can see that the glass can make scratches on the galena. So, we would categorize this mineral
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as hard of a rating five to six, and when picked up, the density is that of a heavy mineral. So,
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this is heavy, black, it's hard, five to six, and it leaves a black streak. Cinnabar is a mineral
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that is characteristic with its dark red coloring. Its luster is metallic. The color, as we said,
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is a dark red, and when taken for the streak test, we can see that it leaves a red, brown, brownish
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red streak. Its hardness cannot be scratched with a fingernail. Copper wire is capable of
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scratching it, so it is considered a soft mineral with a rating of three to four, and it is a middle
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type of heavy for its density. Pyrite is colloquially called fool's gold because of its
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shiny gold-like luster, so we know that it has a highly metallic luster. It is dark brown or black,
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and its streak test is a clear black streak. For its hardness, we can test it. Fingernail makes
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no effect. Copper wire, it's equally impossible to scratch. Even glass does not scratch the pyrite,
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so we can categorize this as a very hard mineral, and its density is that of a heavy mineral.
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Halite is another common mineral. It is rock salt. Its luster is non-metallic. It's gray,
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although very crystallized, and its streak test is white. It leaves a white streak on the porcelain
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tile. In terms of hardness, a fingernail has no effect, but the copper wire can streak it,
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can scratch it, so we know that it can be categorized, again, as soft, so a three to
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four rating, and in terms of density, it's remarkably light. Orthoclast is a non-metallic,
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light brown mineral, and its streak test leaves a white streak, very difficult to see on the tile,
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and this mineral cannot be scratched with a fingernail, cannot be scratched with the copper
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wire, cannot be scratched with glass. It is very hard, so it is one of the hardest minerals we have
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tested yet, with its physical properties, and when held, it's surprisingly light, so its density is
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light. Quartz is a very pretty mineral, and it is non-metallic, but very glassy is its luster,
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so it has a glassy luster, and this quartz is pink. It comes in many colors, but we're looking
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at pink quartz right now for color, and no matter what color the quartz, its streak test is white.
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It cannot be scratched by a copper wire, it cannot be scratched by glass, and this mineral is so hard
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that it can actually, it is capable of scratching glass, so you can see the scratch that it made.
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It is one of the hardest minerals, and it is capable of scratching glass. Another pretty
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mineral is mica. It is very shiny, so it has a highly metallic luster, and the color is a light
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gray or brown. When it makes it for its streak test,
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it leaves a white streak. Shouldn't it be leaving a brown streak right now? It leaves a white streak,
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and in terms of being soft, a fingernail cannot scratch it, but the copper wire can,
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so it is considered a soft mineral, and it is also very light. One of the most remarkable
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physical characteristics of this mineral is that it cleaves in layers. It has layer cleavage,
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so it is very obvious that it will break and even fleck off into layers, which is one of the most
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obvious physical characteristics of this type of mineral. These two types of mica are different
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colors. This is moscovite, and this is viatite, and even though they are white and black,
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they leave the same color scratch, which is white. So although this mica is black,
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it will leave a white scratch, which characterizes it physically as mica. Argonite is a non-metallic
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mineral, so the luster, again, is dull or non-metallic. It is a dark brown color,
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and its streak test produces a white streak. It is scratched by the copper wire, so it is
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considered soft, and it's a light mineral. We're going to test this mineral because of its
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characteristic properties regarding hydrochloric acid. So I have hydrochloric acid in a small
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droplet bottle, and we're going to watch the chemical reaction between the argonite and
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the hydrochloric acid. The reaction is very swift. This is argonite dissolving and bubbling,
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frothing and foaming because of its chemical reactions to the acid on its surface. If this
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mineral were to be immersed in hydrochloric acid, it would dissolve. This glassy mineral is calcite.
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It is non-metallic, but like the quartz, it's very glassy. Its color is white, and its streak test is
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also white. It cannot be scratched by copper wire, but it can be scratched by glass, as we can see.
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It could be considered hard, and it has a chemical composition that reacts to sulfuric acid. We're
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going to test that chemically now with our droplet of sulfuric acid on the surface. You can see it
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immediately reacting to the hydrochloric acid. Carbon dioxide bubbles are being formed on the
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surface, and if this mineral were to be immersed in hydrochloric acid, it would dissolve the way
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that the surface is dissolving and reacting to the single droplet that we're using in this lab.
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Gypsum is a non-metallic, but highly glassy mineral, so its luster is glassy, and its color
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is white, or crystalline, and when it's scratched, the streak test produces a white streak. In terms
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of hardness, this is so soft, it can be scratched by a fingernail, by a human fingernail, so it's
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considered very soft, from one to two, and its density is relatively light.
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- Idioma/s:
- Autor/es:
- Pilar de Miguel Ceñal
- Subido por:
- M Pilar De M.
- Licencia:
- Reconocimiento - No comercial - Sin obra derivada
- Visualizaciones:
- 13
- Fecha:
- 26 de julio de 2023 - 14:41
- Visibilidad:
- Público
- Centro:
- IES SEVERO OCHOA
- Duración:
- 13′ 09″
- Relación de aspecto:
- 5:4 Es el estándar al cual pertenece la resolución 1280x1024, usado en pantallas de 17". Este estándar también es un rectángulo.
- Resolución:
- 720x576 píxeles
- Tamaño:
- 154.63 MBytes
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