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Practical II

Practical II. Handspecimens. Elementary chemical composition. 4000 mineral species with individual mineral names (currently) Within species different polytypes : Quartz: amethyst, citrine, rosequartz , etc.; Beryl: emerald (Cr-rich); aquamarine (Fe-rich)

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Practical II

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  1. Practical II Handspecimens

  2. Elementary chemical composition • 4000 mineral species with individual mineral names (currently) • Within species different polytypes: • Quartz: amethyst, citrine, rosequartz, etc.; • Beryl: emerald (Cr-rich); aquamarine (Fe-rich) • Common minerals contain abundant elements: O, H, Si, Al, Na, Mg, Ca, Fe, K • Lithophile, chalcophile, siderophile, halogenophile

  3. Classification of minerals • Genetic: • According to principal processes by which minerals are formed • Not mineralogical and problematic • Geochemical • Based on principal chemical elements • Irrational: minerals that consist of many elements? • Crystal chemical • Functional relationship between chemical composition • Acceptable • Geochemical and crystal chemical • Very useful

  4. Classification

  5. Silicates

  6. Movie-time!! • Classification of Minerals

  7. Chapter 15 Mineral identification of hand specimens

  8. Movie-time!! Identification of minerals

  9. Stage of crystallisation Euhedral Subhedral Anhedral

  10. Colour, streak and luster Colour: as directly observed Streak: colour of powdered sample Luster: character of light reflected from mineral surface

  11. Mechanical properties • Hardness: 1-10 • Thumbnail 2 • Copper penny 3-4 • Blade of pocket knife 5-6 • Quartz 6-7 • Cleavage: • Number of cleavage planes • Orientation relative to each other • Development of cleavage: Perfect, strong, weak • Fracture: • Irregular break: conchoidal, stepped, splintery • Tenacity: malleable, ductile, plastic, brittle, sectile, elastically or inelastically flexible

  12. Density and specific gravity Density: mass of a unit volume of material Gravity: ratio of the weight of a body and the weight of an equal volume of water (dimensionless)

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