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Symmetry and stereonets. Point symmetry: 32 possible combinations Mirrors, rotation, center of symmetry, rotoinversion 6 crystal systems. 6 crystal systems C-axis has highest rotation or longest growth direction All axes have + and - ends. Stereonets . 3-D projection into 2-D. stereonets.
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Point symmetry: 32 possible combinations • Mirrors, rotation, center of symmetry, rotoinversion • 6 crystal systems
6 crystal systems • C-axis has highest rotation or longest growth direction • All axes have + and - ends
Stereonets • 3-D projection into 2-D
stereonets • Have on them • crystal axes • Crystal faces • Symmetry elements
How to plot crystal faces • Orient block on stereonet • Faces in northern hemisphere are X’s • Faces in southern hemisphere are O’s • Plotting poles to faces (line perpendicular to the crystal face) • Faces in center are horizontal • Faces on edge are vertical • Faces in between are at an angle
How to plot symmetry elements on stereonet • Mirror planes are solid lines • Dashed lines are axes of rotation with no mirror • Use symbols for rotations
How to take stereonet with symmetry elements and plot crystal faces