Assignment 26 - Feldspar, Spodumene, and Diopside Flashcards
What causes moonstone’s adularescence?
Orthoclase moonstone is composed of two feldspar species, both members of the alkali series—orthoclase and albite. The two species are intermingled during formation. When the melt cools and starts to crystallize, the two species separate into stacked, alter- nating layers that scatter light rays in many directions, producing the adularescent phenomenon.
What are the characteristics of top-quality moonstone?
The finest moonstones possess a colorless, semitransparent to nearly transparent appearance and vivid blue adularescence.
What is spectrolite?
The most prized labradorite type is “spectrolite,” a phenomenal labradorite with brilliant spectral hues.
Which gem is marketed as the “all-American” gemstone?
Because many of the sunstone types are unique to the rugged high-desert area in south-central Oregon, they’re being marketed as “all-American” gemstones
Trade term for a highly prized, vivid blue adularescence displayed by the finest moonstone.
Blue sheen
Tiny tension cracks in moonstone that interfere with adularescence and reduce value.
Centipedes
An imitation of aventurine feldspar made of glass that contains small copper crystals.
Goldstone
What is spodumene’s most prized color?
Kunzite is most commonly light pink, but its most valuable colors are intense pink and intense violetish purple.
Where does kunzite get its name?
It’s named after the pioneering gemologist George Frederick Kunz (1856-1932).
Which Big 3 gemstone does chrome diopside resemble?
High clarity and lack of treatment make chrome diopside an effective emerald alternative.
Yellow spodumene is called
A. kunzite.
B. triphane.
C. hiddenite.
D. heliodor.
B. triphane.
The greenish blue feldspar that has gridlike white streaks and resembles turquoise is
A. amazonite.
B. orthoclase.
C. spectrolite.
D. labradorite.
A. amazonite.
Which of the following is the only known commercial source of chrome diopside?
A. Brazil
B. Russia
C. Tanzania
D. Sri Lanka
B. Russia
Light-colored or colorless spodumene can be treated to a kunzite color by
A. heating.
B. diffusion.
C. surface coatings.
D. irradiation followed by careful heating.
D. irradiation followed by careful heating.
Which of the following three basic chemical elements do all feldspars contain?
A. Aluminum, oxygen, and iron
B. Potassium, calcium, and iron
C. Aluminum, oxygen, and silicon
D. Potassium, calcium, and sodium
C. Aluminum, oxygen, and silicon
