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Minerals

Minerals. Properties of Minerals. Naturally Occurring A substance must be formed by processes in the natural world and not created my man in a laboratory. Which ice is considered a mineral an ice cube or ice formed on a mountain? Why?.

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Minerals

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  1. Minerals Properties of Minerals

  2. Naturally Occurring A substance must be formed by processes in the natural world and not created my man in a laboratory. Which ice is considered a mineral an ice cube or ice formed on a mountain? Why? What is a Mineral?A mineral must have the following characteristics:

  3. The mineral cannot form from materials that were once part of a living thing. Is salt a mineral? Is sugar a mineral? Is coal a mineral? Inorganic

  4. A mineral is always a solid, with a a definite volume and shape. Solid

  5. The particles of a mineral line up in a pattern that repeats over and over again. This repeating pattern of a mineral’s particles forms a solid called a crystal Crystal Structure

  6. Cubic (magnetite) Hexagonal (quartz) Tetragonal (rutile) Orthorhombic (sulfur) Monoclinic (azuirite Triclinic (feldspar) Groups of crystals

  7. A mineral always contains certain elements in definite proportions. Most minerals are chemical compounds made of two or more elements. Almost all pure, solid elements are metals. Copper Silver Gold Definite Chemical Composition

  8. Identifying Minerals • There are about 3,800 minerals. • Each mineral has characteristic properties that can be used to identify it.

  9. Easily observed physical property. Color alone is NOT a good way to make an identification. Gold Pyrite Chalcopyrite Color

  10. The streak of a mineral is the color of its powder. Rub a mineral against a piece of unglazed porcelain tile. Color of minerals may vary but streak is always the same. Streak

  11. Luster • Luster describes how light is reflected from a mineral’s surface. • Luster terms: metallic; glassy; submetallic or dull; silky, earthy; waxy, greasy or pearly

  12. Luster of Minerals Metallic Glassy Waxy, greasy or pearly Galena Topaz Talc Submetallic or Dull Silky Earthy Graphite Malachite Hermatite

  13. Density is a property of how much matter there is in a given amount of space. No matter the size of a mineral sample, the density of that mineral always remains the same. Density Formula Density= Mass Volume Density

  14. The way a mineral breaks apart can help to identify it. Cleavage is the tendency of a mineral to cleave, or break, along flat, even surfaces. The arrangement of atoms in the mineral causes it to break apart more easily in one direction than another. Some minerals have cleavage in more than one direction. Cleavage

  15. Fracture describes how a mineral looks when it breaks apart in an irregular way Fracture is the tendency of some mineral to break unevenly along curved or irregular surfaces. Fracture

  16. Hardness • Hardness is a measure of the resistance of a mineral to being scratched. • Friedrich Mohs (1812) created a test to describe the hardness of minerals. • Moh’s Hardness Scale consists of 10 minerals arranged from 10 (hardest) to 1 (softest). • A mineral can scratch any mineral softer than itself, but can be scratched by any mineral that is harder.

  17. Moh’s Hardness Scale • TALC The softest known mineral, talc flakes when scratched by a fingernail.

  18. Moh’s Hardness Scale • Gypsum A fingernail can easily scratch it.

  19. Moh’s Hardness Scale • Calcite A fingernail cannot scratch it, but a copper penny can.

  20. Moh’s Hardness Scale • Fluorite A steel knife can easily scratch it.

  21. Moh’s Hardness Scale • Apatite A steel knife can scratch it.

  22. Moh’s Hardness Scale • Feldspar It can’t be scratched by a steel knife, but it can scratch window glass.

  23. Moh’s Hardness Scale • Quartz It can scratch steel and hard glass easily.

  24. Moh’s Hardness Scale • Topaz It can scratch quartz.

  25. Moh’s Hardness Scale • Corundum It can scratch topaz.

  26. Moh’s Hardness Scale • Diamond The hardest known mineral, diamond can scratch all other substances.

  27. Special Properties • Some properties are particular to only a few types of minerals. • These properties include: • Fluorescence: Does it glow under ultraviolet light? • Chemical Reaction: Will a mineral effervesce or “fizz” when a drop of weak acid is placed on it? • Optical properties: Will the mineral bend light to produce a double image? • Taste: Does the mineral taste salty? • Magnetism: Will the mineral attract iron?

  28. Magnetism: Magnetite attracts these iron metals Fluorescence: Scheelite glows in ultraviolet light. Optical Properties: Calcite bends light to produce a double image Reactivity: Aragonite reacts chemically to acids.

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