Fun facts about quartz

Roman naturalist Pliny the Elder (AD 23 - AD 79)

believed that quartz was:

• The frozen teardrops of geologists

• Frozen sunbeams

• Frozen water ice

• Frozen lightening

Answer explanation

"Roman naturalist Pliny the Elder believed quartz to be water ice, permanently frozen after great lengths of time.

The word "crystal" comes from the Greek word κρύσταλλος, "ice".

He supported this idea by saying that quartz is found near glaciers in the Alps, but not on volcanic mountains, and that large quartz crystals were fashioned into spheres to cool the hands. This idea persisted until at least the 17th century."

https://en.wikipedia.org/wiki/Quartz

According to McQueen (2018), 182 kg of quartz was mined from the ~74 quartz-rich pipes at Kingsgate, NSW during World War 2. The quartz was mined because of ...

• its use as a precious gemstone to boost the economy.

• its use as a semiconductor in the early computing industry.

• its piezoelectric properties and use in radio transmitters.

• its tensile strength for use in manufacturing missiles.

Answer explanation

"During the tin rush of the early 1870s, an Adelaide company discovered unusual quartz-rich pipes containing bismuth, molybdenum and minor tungsten mineralisation near Kingsgate, 25 km east of Glen Innes. At least 70 pipes were eventually discovered, with production coming from 54."

(McQueen, 2018, Technical Report, p. 9)

In the 17th century, Danish scientist Nicolas Steno defined many of the principles of stratigraphy that are still used today.

However, he also discovered that regardless of a quartz prism’s size or shape, adjacent prism faces of quartz always meet at an angle of ...

• 30^o

• 60^o

• 90^o

• 120^o

Answer explanation

"In 1669 Nicolaus Steno studied many quartz crystals and found angles between adjacent prism faces, termed interfacial angles, to be 120^o no matter how the crystals had formed."

Perkins, 2022, Mineralogy

The worlds "largest quartz crystal cluster" is on display at the Crystal gallery, Swakopmund, Namibia.

How much does it weigh?

• 4,100 kg

  (4.1 tons)

• 14,100 kg

  (14.1 tons)

• 141,000 kg

  (141 tons)

• 1410,000 kg

  (1410 tons)

Answer explanation

"The world’s largest quartz crystal cluster was discovered in 1985 at the Otjua Mine near Karibib in Namibia. Found at the bottom of a 45-meter deep cave, this massive quartz cluster weighs an impressive 14,100 kg. The excavation process was a significant undertaking, taking a full three years to complete."

https://rockseeker.com/worlds-largest-quartz-cluster/?

Artificially heat-treating amethyst between 400-600^oC transforms amethyst to:

• citrine

  (yellow quartz)

• prasiolite

  (green quartz)

• smokey quartz

  (dark brown to grey quartz)

• clear, colourless quartz

Answer explanation

"The color at different temperatures can be divided into three stages: The amethyst stage with temperature below 420 °C, the prasiolite stage with temperature between 420 and 440 °C where the color center is the most unstable, the citrine stage with temperature above 440 °C. The color change degree of heated amethyst is related to its initial color. When the initial color is darker, the color difference of heated amethyst is larger, and the easier it is to change the color after heat treatment."

Cheng & Guo, 2020, Scientific Reports