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Crystal Forms

Crystal Forms. www.intenseexperiences.com/images/CaveofCrystals2.jpg. Crystal Forms. Minerals grow into specific shapes They usually crystallize into one of 6 forms Cubic Tetragonal Hexagonal Orthorhombic Monoclinic Triclinic. Axes of Symmetry.

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Crystal Forms

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  1. Crystal Forms www.intenseexperiences.com/images/CaveofCrystals2.jpg

  2. Crystal Forms Minerals grow into specific shapes They usually crystallize into one of 6 forms Cubic Tetragonal Hexagonal Orthorhombic Monoclinic Triclinic

  3. Axes of Symmetry • Lines about which a mineral can be rotated through some angle which brings the object to a new orientation which appears identical to its starting position.

  4. Cubic • Crystals shaped like blocks • 3 axes of symmetry • All the same length • All perpendicular to each other

  5. Cubic Example: Pyrite http://www.treasuremountainmining.com

  6. Tetragonal • Crystals shaped like four-sided prisms and pyramids. • Three axes of symmetry • Two axes are the same length and lie on a horizontal plane. • The third axis is not the same length and is at a right angle to the other two. • All perpendicular to each another.

  7. Tetragonal Example: Zircon www.dkimages.com

  8. Hexagonal • Crystals are shaped like six-sided prisms or pyramids. • Four axes of symmetry • Three lie in the same plane, are the same length, and intersect at 120° angles. • The fourth axis is not the same length, and is perpendicular to other three.

  9. Hexagonal Example: Beryl www.palagems.com

  10. Orthorhombic • Crystals are short and stubby. • 3 axes of symmetry • All unequal lengths • All perpendicular to each other.

  11. Orthorhombic Example: Topaz http://www.collectorfinejewelry.com

  12. Monoclinic • Crystals are short and stubby with tilted faces at each end. • 3 axes of symmetry • All unequal lengths • Two axes lie in the same plane at right angles to each other. • The third axis is inclined.

  13. Monoclinic Example: Gypsum http://www.galleries.com/minerals/property/gyp_flu.gif

  14. Triclinic • Crystals are usually flat with sharp edges, with no right angles. • 3 axes of symmetry • All unequal lengths • None are perpendicular to one another.

  15. Triclinic Example: Feldspar www.yourgemologist.com

  16. Credits • http://www.sdnhm.org/kids/minerals/howto-form.html (information) • www.gemsociety.org/ wow/read2.htm (form model images) • http://www.georgehart.com/virtual-polyhedra/symmetry_axes.html (axes of symmetry definition

  17. ASSIGNMENT • PG 63 SHOWS THE SIX MAIN CRYSTAL SYSTEMS • YOU NEED TO MAKE 3-DEMENSIONAL MODELS OF THE 6 MAIN CRYSTAL SYSTEMS • MAKE SURE TO LABEL EACH MODEL WITH THE SYSTEM NAME AND YOUR NAME

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