"All written work appears to the right of the red margin line ..... a crystal are perpendicular to the crystal faces and intersect in the center of the crystal. ... 28. What factors in nature can prevent natural crystals from forming with all faces visible? ..... Eventually, different layers, or zones, of soil become noticeable" (www.lcps.org/cms/lib4/VA01000195/.../2014%20semester%202%20Booklet.pdf)
Hope this helps