GEO 331 EXAM TEST QUESTIONS WITH ACCURATE
SOLUTIONS
1) Color in gemstones is often produced by -- Answer ✔✔ - color centers
- absorption of specific light wavelengths
- reflection of specific light wavelengths
- impurities
2) Light is bent when it passes into a crystal because -- Answer ✔✔ -the density of
the crystal is greater than the density of air
3) Opal differs from crystalline quartz because -- Answer ✔✔ -Opal can contain a
great deal of water, while quartz contains none
4) Citrine is -- Answer ✔✔ -a type of SiO2 containing Fe impurity often formed by
heat treatment of amethyst
5) Heat treatment of sapphires results in -- Answer ✔✔ - not increased rutile
inclusions.
- not increasing the refractive index of a gem
- not oiling the surface to make it more opaque
- not removing blue light wavelengths from within the gem
SOLUTIONS
1) Color in gemstones is often produced by -- Answer ✔✔ - color centers
- absorption of specific light wavelengths
- reflection of specific light wavelengths
- impurities
2) Light is bent when it passes into a crystal because -- Answer ✔✔ -the density of
the crystal is greater than the density of air
3) Opal differs from crystalline quartz because -- Answer ✔✔ -Opal can contain a
great deal of water, while quartz contains none
4) Citrine is -- Answer ✔✔ -a type of SiO2 containing Fe impurity often formed by
heat treatment of amethyst
5) Heat treatment of sapphires results in -- Answer ✔✔ - not increased rutile
inclusions.
- not increasing the refractive index of a gem
- not oiling the surface to make it more opaque
- not removing blue light wavelengths from within the gem
