CS 20 Flashcards
he trade term “black onyx” is used for
treated black chalcedony
Cryptocrystalline quartz aggregate is known as
chalcedony
Most of the citrine in the market is
produced by heating amethyst
The world’s major commercial-quality amethyst source is
Brazil
The major producer of green aventurine quartz is
India
Chalcedony with curved or angular bands or layers that differ in color and transparency is known as
agate
Which of the following has the smallest crystal size?
Cryptocrystalline aggregates
Both tiger’s-eye and hawk’s-eye quartz are
microcrystalline aggregates
The color of chrysoprase is
yellowish green
The only source of natural ametrine is
Ametrine
In the nineteenth century, a major source of amethyst was discovered in
Brazil
Dark amethyst is lightened by
heating
The finest amethyst colors are
medium-dark to dark reddish purple or purple.
“Marabá” amethyst is often
uniform in color. Marabá amethyst is often less saturated in color than amethyst from other Brazilian sources, but its color is more uniform
The color of amethyst results from
color centers acting on iron.
