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How to Measure Interfacial Angles

Geologists and amateur crystal enthusiasts enjoy the process of examining gems such as quartz crystals, which have numerous faces on the surface. Each face has edges that form interfacial angles that are unique to the crystal's identification. It is possible to measure these angles for scientific research or hobbyist pleasure, with the correct tools. Some schools use interfacial angle measurements in science experiments for determining gem features and crystal formation.

Things You'll Need

Crystal
Contact goniometer
Paper
Pen
Pencil

Instructions

- 1
  Place the crystal on a table or other steady work surface. Make sure that the gem is in a stationary position for accurate measurements.
- 2
  Place the contact goniometer's flat ruler side against one facial edge. Hold the tool and crystal together with your hands.
- 3
  Rotate the protractor side of the contact goniometer so it is flush against the adjacent edge of the crystal. If it's equipped with a locking feature, lock the contact goniometer's protractor side in this position for greater accuracy.
- 4
  Read the far outside value that the protractor side points to on the number line. The number line is a set of sequential angles; the outside value along the contact goniometer's edge is the interfacial angle.
- 5
  Note the interfacial angle value on a piece of paper, with a pen or pencil.
- 6
  Remove the contact goniometer from the crystal. Repeat Steps 2 to 5 for other facial edges, if desired.

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