Geol. 198B Homework #5: Magnification and What it Reveals 20 pts. **

The answers to the following questions will be found in the text reading assignments, and the assigned web essays for Lesson 5.

Required Format: A 2 point penalty will be deducted for not following the format described (even if all the answers are correct)!

Send the answers to me, as an email through WebCT. Use "Homework #5" as the subject line.

As the body of the email, the answers should be arranged vertically, single file, like so:

1. b

2. quartz

3. False

4. etc....

All required answers for Homework #5 are: a multiple choice letter, True/False, or one word.

When the time period for homework submission has passed, grades will be posted which you may then view using the "My Grades" function of WebCT through the course home page.


1. True or False. A "pinwheel" is actually a type of "reflector" inclusion.


2. When an inclusion is oriented along the crystal axes of a material, it is a sign that it:

a. was formed before the host crystal

b. formed along with the host crystal

c. formed after the host material had already crystallized

d. formed in a laboratory, so the material is a synthetic

e. none of the above

3. The most common inclusion to be found in quartzes is:

a. feathers

b. horsetails

c. pyrite

d. tourmaline

e. none of the above

4. Rubellite gets its red color from:

a. crystal lattice defects

b. manganese

c. iron

d. vanadium

e. none of the above

5. Lyman states that careful microscopic examination of inclusions is particularly useful in distinquishing the mine location of rubies and:


6. In order for a "starburst" inclusion to form in quartz, both golden rutile and black___________ must be present.


7. What is the species of solid crystal in Arizona peridot which forms part of the lily pad inclusion?


8. The included material which stains the channels in Indonesian chalcedony, sometimes creating what look like symbols or letters, gets its color from:

a. dispersion

b. iron

c. rutile

d. growth phantoms

e. manganese

9. GIA labels rubellite tourmaline as a Class III gem, which means:

a. it is rarely included

b. it has very high dispersion

c. its color comes from crystal lattice defects

d. it is almost always included

e. it is sometimes included

10. White quartzite rock containing crystals of _________ is a popular jewelry material.

a. gold

b. apatite

c. tourmaline

d. iron oxide

e. pyrite

** "A Word to the Wise": In order to get the full 20 points on this, and every other homework, you must have all the correct answers, they must be in proper format as described above AND your email to me must be received and logged in by WebCT before the closing time for the assignment. As there are inevitable computer downtimes, disconnects and other such issues, I suggest that you do not wait until the very last moment to attempt to submit the work.