Question

Recognize the gemstone peridot (gem variety of olivine) and the four main gem varieties of the quartz family (opal, amethyst, citrine, and agate) by using their distinguishing physical properties (e.g., colour, banding, optical effects, etc.).

Answer 1

Peridot is known for its green-yellow color, while the quartz family members like opal show play-of-color, amethyst is purple due to iron, citrine is yellow to orange and agate features multicolored banding.

Step-by-step explanation:

Identifying Gemstones by Their Physical Properties:

To recognize the gemstone peridot (gem variety of olivine) and the four main gem varieties of the quartz family including opal, amethyst, citrine, and agate, we can look at distinguishing physical properties such as color, banding and optical effects.

Peridot:

Peridot tends to have a characteristic green-yellow color, which comes from the presence of iron. It is part of the olivine mineral group found in ultramafic rock peridotite.

Quartz Varieties:

1. Opal is known for its unique play-of-color, an optical effect displaying a rainbow-like hue which changes with the angle of observation.
2. Amethyst is recognized by its distinctive purple color, which is due to trace amounts of iron in the quartz.
3. Citrine possesses a yellow to orange hue; it's a rare natural quartz variant.
4. Agate features a banding of multiple colors and is usually translucent to opaque.

While color can be altered by environmental factors or treatments and may not always be diagnostic these physical properties are usually indicative of the listed gems.