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Bladh provides a guide to the essential observations that allow visual recognition of the morphological crystal systems. The techniques explained herein will work for most undistorted crystals larger than a few centimeters. A useful observation to describe the shapes created on three-dimensional solids by the exterior surfaces (called faces on mineral crystals) is the angle created on a face by the edge intersections at a corner where three edges meet. Although some faces are still rectangles or squares, two new flat shapes are present (hexagons and parallelograms), and most of their corner-edge junctions meet at angles greater or less than 90 degrees. Two other common shapes for crystal faces are the rhombus (a parallelogram with four equal edges) and the triangle.