Properties of Minerals as an Aid to Identification
Minerals possess a number of physical properties that aid in their identification. These are listed below with a brief description:
Color--The color of the specimen as it appears to the naked eye under normal lighting conditions. Some minerals such as gold will only appear as one color, but due to impurities and Crystal Light distortion, many minerals can appear in multiple colors. Therefore, observable specimen color is the least effective property in identification.
Streak--The color of a mineral in powdered form. A streak test is performed by dragging a freshly cleaved mineral surface across an unglazed porcelain surface. If the mineral is less hard than the porcelain, it will leave a stripe of color (the mineral in a powdered state). This is the true color of a mineral specimen as it lessens the impurity impact and eliminates the light distortion from the crystal. Although a mineral may have multiple observable specimen colors, it will only have one streak color.
Luster--Refers to the absorption, reflection, or refraction of light by the surface of a mineral. Minerals possess various lusters that are somewhat self-explanatory such as dull, earthy, adamantine, metallic, glassy, metallic, silky, greasy, pearly, and resinous.
Fluorescence--Some minerals fluoresce in ultraviolet light, and some minerals specimens may appear to fluoresce due to fluorescent mineral impurities, or due to locality. This is not an extremely reliable indicator property but can be used in conjunction with other identification properties.
Chemical Composition--Minerals are chemicals, either elements or compounds found naturally in the Earth. Some minerals have a fixed chemical composition, and some minerals have a rigid set of chemical composition parameters that allow for the replacement of certain elements with other elements. Chemical properties can be tested with the use of a blowpipe, flame color, bead test, and laboratory solution tests.
Hardness--Minerals are identified roughly by their hardness based on the Mohs scale of mineral hardness, a list of ten minerals from #1 (softest) to #10 (hardest). All minerals will fall somewhere along the scale, based on their ability to scratch any mineral with a number lower than theirs and their inability to scratch any mineral with a number higher than theirs.
Mohs Scale of Mineral Hardness:
Specific Gravity--Is the relative weight of a mineral as compared to the weight of an equal volume of water. The specific gravity is also referred to as density and is expressed normally as an average of a small range of densities.
Some Common Minerals and Their Specific Gravity:
Crystal Form--A mineral's crystals form into one of six mineral crystal systems: cubic, tetragonal, hexagonal, orthorhombic, monoclinic, or triclinic. The crystal form reflects the structure of the molecules and formation environment of the mineral. Although sometimes difficult, identification of a mineral's crystal form is an invaluable aid to mineral identification along with the other mineral properties.
Optical Properties--Used mainly be scientists, X-rays are sent through thin slices of mineral, producing identifying patterns of light which measure their index of refraction which is distinct for each mineral.
Cleavage--The way some minerals split along planes which are related to their mineral structure, parallel to any crystal faces. Cleavage is measured in degrees of perfection from poor, to fair, good, perfect, and eminent, and are described by the number and direction of cleavage planes. Some minerals do not show cleavage, but fracture in a way other than along any cleavage plain.
Magnetism--Certain minerals exhibit magnetism or an attraction to a magnet, and some will display this property only when heated.
Electrical Properties--Some minerals when heated or rubbed will develop an electrical charge. Others will be able to control radio frequencies.
Melting Point--A pure mineral will posses a melting point which can be tested with a high temperature flame until it fuses at the edges.
Color is least useful in identifying a mineral because the color can vary in each form of the mineral. The most useful way to identify a mineral is streak.
Probably the most useful characteristic in mineral identification is the chemical composition. But because most people do not have access to laboratory equipment, hardness and streak would be the most useful in the field.
=== === === === The following is a list of most of the mineral properties that can be observed or tested:
Color--The color of the specimen as it appears to the naked eye under normal lighting conditions. Some minerals such as gold will only appear as one color, but due to impurities and Crystal Light distortion, many minerals can appear in multiple colors. Therefore, observable specimen color is the least effective property in identification. Streak--The color of a mineral in powdered form. A streak test is performed by dragging a freshly cleaved mineral surface across an unglazed porcelain surface. If the mineral is less hard than the porcelain, it will leave a stripe of color (the mineral in a powdered state). This is the true color of a mineral specimen as it lessens the impurity impact and eliminates the light distortion from the crystal. Although a mineral may have multiple observable specimen colors, it will only have one streak color. Luster--Refers to the absorption, reflection, or refraction of light by the surface of a mineral. Minerals possess various lusters that are somewhat self-explanatory such as dull, earthy, adamantine, metallic, glassy, metallic, silky, greasy, pearly, and resinous. Fluorescence--Some minerals fluoresce in ultraviolet light, and some minerals specimens may appear to fluoresce due to fluorescent mineral impurities, or due to locality. This is not an extremely reliable indicator property but can be used in conjunction with other identification properties. Chemical Composition--Minerals are chemicals, either elements or compounds found naturally in the Earth. Some minerals have a fixed chemical composition, and some minerals have a rigid set of chemical composition parameters that allow for the replacement of certain elements with other elements. Chemical properties can be tested with the use of a blowpipe, flame color, bead test, and laboratory solution tests. Hardness--Minerals are identified roughly by their hardness based on the Mohs scale of mineral hardness, a list of ten minerals from #1 (softest) to #10 (hardest). All minerals will fall somewhere along the scale, based on their ability to scratch any mineral with a number lower than theirs and their inability to scratch any mineral with a number higher than theirs. Mohs Scale of Mineral Hardness # Talc
# Gypsum
# Calcite
# Fluorite
# Apatite
# Orthoclase
# Quartz
# Topaz
# Corundum
# Diamond
Specific Gravity--Is the relative weight of a mineral as compared to the weight of an equal volume of water. The specific gravity is also referred to as density and is expressed normally as an average of a small range of densities. Some Common Minerals and Their Specific Gravity # Halite (2.1)
# Gypsum (2.3)
# Quartz (2.7)
# Talc (2.8)
# Muscovite Mica (2.8)
# Corundum (4.0)
# Cinnabar (8.0)
# Gold (19.3)
Crystal Form--A mineral's crystals form into one of six mineral crystal systems: cubic, tetragonal, hexagonal, orthorhombic, monoclinic, or triclinic. The crystal form reflects the structure of the molecules and formation environment of the mineral. Although sometimes difficult, identification of a mineral's crystal form is an invaluable aid to mineral identification along with the other mineral properties. Optical Properties--Used mainly be scientists, X-rays are sent through thin slices of mineral, producing identifying patterns of light which measure their index of refraction which is distinct for each mineral. Cleavage--The way some minerals split along planes which are related to their mineral structure, parallel to any crystal faces. Cleavage is measured in degrees of perfection from poor, to fair, good, perfect, and eminent, and are described by the number and direction of cleavage planes. Some minerals do not show cleavage, but fracture in a way other than along any cleavage plain. Magnetism--Certain minerals exhibit magnetism or an attraction to a magnet, and some will display this property only when heated. Electrical Properties--Some minerals when heated or rubbed will develop an electrical charge. Others will be able to control radio frequencies. Melting Point--A pure mineral will posses a melting point which can be tested with a high temperature flame until it fuses at the edges.
Hardness, streak, specific gravity, chemical composition, and crystal form should be about it.
i believe that hardness is used bes to identify minerals
mineral content
mineral content
Mineral content
In classifying rocks, there are many properties that can be useful. In my opinion, either color or texture is most useful in classifying a rock or mineral.
Limestone is the rock that is most useful to modern industrial countries because it is the source for the main ingredient in cement.
One of the main methods of identifying rocks is by their method of formation. Igneous rock from melt; metamorphic rock from heat/pressure;sedimentary rock from lithification of sediment or precipitation. Then add in the myriad of possible combinations and percentages of minerals that may comprise the rock, and sometimes the identification of a rock can be a daunting task. Minerals are identified by their chemical composition, their crystalline structure, their specific gravity, hardness, streak, and other physical properties.
mineral content
Its mineral composition.
Mineral content
In classifying rocks, there are many properties that can be useful. In my opinion, either color or texture is most useful in classifying a rock or mineral.
i think so because it each sedimentary rock has its own property, and color is an important one
chbdhcbajscnn SNlnxjdjdjdj
Igneous rock. If you are in FIS you know me. O.K.
Limestone is the rock that is most useful to modern industrial countries because it is the source for the main ingredient in cement.
Igneous rock. If you are in FIS you know me. O.K.
slate and marble
Sedimentary
The streak of a mineral is much more accurate in identifying a mineral than color. The streak of a mineral can distinguish minerals with metallic and non-metallic luster. For example, metallic minerals generally have a dark streak whereas non-metallic luster minerals often have a light colored streak.