Geol. 115 Study Guide for Lesson Five

What do you need to know (meaning understand, not just memorize) to do spectacularly well on Quiz 5? 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

silk, "lily pad", "horsetail", loupe, triplet loupe, chromatic and spherical distortion, darkfield, brightfield, overhead (incident/reflected) lighting, baffle, iris diaphragm, blemishes, inclusions, exsolution, two phase and three phase inclusions, "feathers", "fingerprints", cleavage rainbow, striae, flawless, eyeclean, slightly included, included, reflector inclusions, "stab in the heart" inclusions.

2) Essential Concepts

Three reasons why magnifying gemstones is necessary and useful with examples, various types of loupes and their best uses, using a 10x loupe: technique, significance of focal length, focal area and lighting, gem microscopes: main lighting options, defintions, comparisons and best use for each with examples, defintion of blemishes vs inclusions with examples of each and their relevance, Four groups of inclusions and other internal features: solids: types, examples, how formed, cavities: bubbles (significance and how identified) two and three phase inclusions, cracks: types, names and significance, growth phenomena: examples and signficance. Clarity grading of gems: difference between standards for colored stones and diamonds, basic terminology used, which clarity characteristics are least important vs most important in setting grade, examples where inclusions increase gem value and how those gems are clarity graded.

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.)

Sphene, bryssolite, demantoid, loupe, vanadinite, enhydro, trigons, exsolution, striae, trapiche.