Geol. 115 Study Guide for Lesson Six

What do you need to know (meaning understand, not just memorize) to do spectacularly well on Quiz 6? The essential terms and concepts are listed below. Writing out answers to each of the following would be an excellent way to prepare.

(Be able to define or recognize the definition of these terms and understand their useage in context). You can find the information in the web lesson -- on your test, do not expect exactly the same wording or examples as in your lesson. It would be a good idea to cross reference the defintions in the lesson with those you find in the texts.)

1) Essential Vocabulary

Iridescence, orient, Labradoresence, adularescence, aventurescence, chatoyancy, cat'seye effect, asterism, color change, diffraction, interference, nacre, conchiolin, cleavage rainbow, opalescence, play of color, shiller, girasol effect, goldstone, cat'seye tricks: milk and honey and opening and closing, Alexandrite effect.

2) Essential Concepts

Defintion optical phenomena vs optical properties, define and give examples of the major optical phenomena in gemstones, structure of pearl and of its nacre, cause of iridescence, cause of orient, relationship between color and size of internal structures which cause iridescence, causes of Labradorescence, and adularescence (shiller) in moonstone, why "fire" is not a correct term for the optical phenomenon seen in precious opal, difference between common and precious opal, examples of man-made iridescence in gems, defintion and examples of girasol effect, correct spelling and pronunciation of aventuresence, chatoyance vs cat'seye effect and asterism: similarities and differences. How are cat'seyes and stars produced in cutting and viewing a gem?, how cat'seye gems are named, what causes color change phenomenon, which is the most valuable color change gem?

3) Pronunciation Guide

(Clicking on the term will temporarily take you to a new web page to hear the pronunciation of the word. Depending on your browser configuration either put away the audio window, or use the back button to return to the list.)

Labradorescence, adularescence, aventurescence, chatoyance, nacre, conchiolin, opalescence, girasol, shiller, Charoite, serefinite.