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How to Measure Quartz Crystal Parameters

Quartz is a silicate mineral, meaning that its chemical composition is SiO2 or one silicon and two oxygen molecules. The silicon-oxygen bond is very strong, which gives quartz its extreme hardness and strength.

When other elements are included in the recipe for quartz in small amounts, quartz will form in different colors. For example, trace amounts of titanium, iron or manganese can give quartz a pinkish color and is therefore called "rose quartz." There are several varieties of quartz including smokey (grey), amethyst (purple), citrine (yellow) and jasper (red or brown).

Instructions

- 1
  
  Only the perfect conditions will allow individual quartz crystals to grow.
  
  Determine that the quartz displays individual crystals. Quartz has the opportunity to grow into perfect crystals but the environment and conditions in which they grow are very particular.
  
  Quartz is formed when magma cools slowly and molecules of silicon and oxygen are able to bond together. The longer and slower the cooling process, the more likely it is that crystals will have time to form. However, disruptions or quick cooling will change the formation of quartz, giving it a smooth texture, without allowing crystals to form.
- 2
  
  Nature produces irregular crystal growth and double termination is rarely seen.
  
  Determine the crystal class and shape of the quartz. Although the environment for crystal growth must be ideal, crystals are not uncommon. These crystals display a hexagonal, or six-fold, symmetry. Typically, the shaft of the crystal will display a six-sided mirror image of itself, and it will be topped by a six-sided pyramidal structure. This is termed the hexagonal-pyramidal class.
  
  In perfect conditions, which are rare in nature and more often seen in man-made crystals fabricated in a lab, a quartz crystal can have a pyramid at both ends of the hexagonal shaft. These are considered "doubly terminated" quartz crystals.
- 3
  
  This 3-D hexagonal prism demonstrates the lattice parameters.
  
  Measure the lattice parameters of the hexagonal and pyramidal structures. A crystal is made up of an arrangement of atoms at different lattice points for any three-dimensional structure. The lattice points and planes are determined by the crystal class; in the case of quartz, the hexagonal-pyramidal class. These parameters are the length of the edges and the angles between them.
  
  Using this data, the total volume of a crystal can be calculated as well. Use the formula:
  
  √3 a2 c
  
  ---------
  
  2
  
  where a and c are lattice vectors. The final result gives the volume of the hexagonal prism and pyramid.
- 4
  
  The clock face identifies it as being run with a quartz crystal.
  
  Determine the crystal's piezoelectric characteristics. Quartz crystals can display a unique trait known as piezoelectricity whereby the crystal produces a very regular electric current when pressure is applied to both ends. As mentioned earlier, perfect quartz crystal growth can result in pyramid structures at both ends of the hexagonal prism. These doubly terminated specimens perform the best.
  
  This current has been harnessed in many manufactured goods, most notably in watches. Notice that many watches and clocks have the word "quartz" emblazoned right on their faces, identifying those pieces as keeping time with doubly terminated quartz crystals, which emit an electric current at the regular interval of one per second.

Rocks & Minerals