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Bellringer : What is a mineral?

Bellringer : What is a mineral?. Physical Properties of Minerals. mineralogist a person who examines, analyzes, and classifies minerals Each mineral has specific properties that are the result of its chemical composition and crystalline structure .

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Bellringer : What is a mineral?

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  1. Bellringer: • What is a mineral?

  2. Physical Properties of Minerals • mineralogista person who examines, analyzes, and classifies minerals • Each mineral has specific properties that are the result of its chemical composition and crystalline structure. • These properties provide useful clues for identifying minerals. • Many of these properties can be identified by simply looking at a sample of the mineral or through simple tests.

  3. Color • While a mineral’s color is easy to observe, it alone is not a reliable clue for identifying a mineral sample. • The color of a mineral sample can be affected by the inclusion of impurities or by weathering processes. • Streak • streakthe color of a mineral in powdered form • Streak is more reliable than color for the identification of minerals. • Streak is determined by rubbing some of the mineral against an unglazed ceramic tile called a streak plate.

  4. Luster • luster the way in which a mineral reflects light • A mineral is said to have a metallic luster if the mineral reflects light as a polished metal does. • All other minerals have nonmetallic luster. • There are several types of nonmetallic luster, including glassy, waxy, pearly, brilliant, and dull or earthy.

  5. Click below to watch the Visual Concept.

  6. Cleavage and Fracture • cleavagethe tendency of a mineral to split along specific planes of weakness to form smooth, flat surfaces • fracturethe manner in which a mineral breaks along either curved or irregular surfaces

  7. Click below to watch the Visual Concept.

  8. Hardness • The measure of the ability of a mineral to resist scratching is called hardness. Hardness does not mean “resistance to cleavage or fracture.” • The hardness of a mineral can be determined by comparing the mineral to minerals of Mohs hardness scale. • Mohs hardness scalethe standard scale against which the hardness of minerals is rated • The strength of the bonds between the atoms that make up a mineral’s internal structure determines the hardness of that mineral.

  9. The diagram below shows Mohs Hardness Scale.

  10. Physical Properties of Minerals, continued • Reading Check • What determines the hardness of a mineral? • The strength and geometric arrangement of the bonds between the atoms that make up a mineral’s internal structure determine the hardness of a mineral.

  11. Crystal Shape • A mineral crystal forms in one of six basic shapes. • A certain mineral always has the same general shape because the atoms that form the mineral’s crystals always combine in the same geometric pattern.

  12. The six basic crystal systems are: • 1. isometric or cubic system • 2. the orthorhombic system • 3. the tetragonal system • 4. the hexagonal system • 5. the monoclinic system • 6. The triclinic system.

  13. The diagram below shows the six basic crystal systems.

  14. Density • densitythe ratio of the mass of a substance to the volume of the substance • The density of a mineral depends on the kinds of atoms that the mineral has and on how closely the atoms are packed.

  15. A few minerals have some additional, special properties that can help identify those minerals. • Fluorescence and Phosphorescence • The ability to glow under ultraviolet light is called fluorescence. • The property of some minerals to glow after the ultraviolet light is turned off is called phosphorescence.

  16. Chatoyancy and Asterism • In reflected light, some minerals display a silky appearance that is calledchatoyancy, or the cat’s-eye effect. • A similar effect called asterism is the phenomenon in which a six-sided star appears when a mineral reflects light.

  17. Double Refraction • The property of some minerals, particularly some forms of calcite, to produce a double image of any object viewed through the mineral is called double refraction.

  18. Special Properties of Minerals, continued • Reading Check • What is the difference between chatoyancy and asterism? • Chatoyancy is the silky appearance of some minerals in reflected light. Asterism is the appearance of a six-sided star when a mineral reflects light.

  19. Special Properties of Minerals, continued • Magnetism • Minerals that are attracted to magnets display the property of magnetism. These minerals may be magnetic themselves. • In general, nonsilicate minerals that contain iron are more likely to be magnetic than silicate minerals are.

  20. Radioactivity • The property known as radioactivity results as unstable nuclei decay over time into stable nuclei by releasing particles and energy. • A Geiger counter is used to detect the released particles and, thus, to identify minerals that are radioactive.

  21. Virginia: Stone, cement, sand and Gravel • Rock and Mineral Production in the United States

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