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A quartz crystal begins with a seed of one silicon atom and two oxygen atoms. With the right amount of heat and pressure this seed starts to grow by replicating itself in a network structure, known as a crystal lattice. Over time a piece of pure transparent quartz crystal is formed. In its natural state the crystal is angular in shape, always with six sides, tapering at the end to a point or termination. The tapered sides are known as facets or faces. One of these facets or faces will be larger than the others and is referred to as the main facet or face.
I took this photo at Peterson's Rock Garden this last summer with the grandkids.