You know how some celebrities achieve a certain level of success and then you start seeing them everywhere? Well, if there’s an equivalent in the mineral world, it would have to be quartz. As an individual mineral it is the most common mineral on Earth. Quartz is a silicate mineral, meaning that it is made up of a combination of silicon and oxygen atoms. It’s difficult to come up with a unifying description for the mineral, as quartz can be found in a variety of different forms and colors. Gemstone varieties of quartz are among some of the mineral’s most popular forms. Let’s get to gem hunting; there are more than a few diamonds in the rough here.
By analyzing questions, you can see patterns emerge, patterns that will help you answer questions. Qwiz5 is all about those patterns. In each installment of Qwiz5, we take an answer line and look at its five most common clues. Here we explore five clues that will help you answer a tossup on quartz.
BOWEN’S REACTION SERIES
Minerals are often formed by the cooling of magma. In the early 20th century the geologist N.L. Bowen performed experiments to determine the order in which different silicate minerals formed as magma cools. The resulting progression is known as Bowen’s Reaction Series. Quartz occurs at the very low end of the reaction series, meaning that various forms of quartz crystalize from magma at a lower temperature.
GOLDICH SERIES
If Bowen’s Reaction Series describe the formation of silicate minerals, Goldich’s Series can be thought of as a timeline of their dissolution. Samuel Goldich identified which minerals are most susceptible to weathering and which are least. Quartz is among one of the least susceptible elements to weathering, largely due to the strength of its molecular bonds.
PIEZOELECTRIC PROPERTIES
When quartz is compressed or struck, it generates a small electrical current. Additionally, if you run an electrical current through quartz it changes its shape slightly. This behavior is known as the piezoelectric effect. Certain clocks take advantage of the piezoelectric effect to measure time by applying a consistent electric current to a piece of quartz and counting the resulting number of pulses.
CITRINE AND AMETHYST
Quartz comes in many shapes, sizes, and colors. The vibrant, violet amethyst is a semiprecious variant of quartz that can often be found in geodes—hollow rocks filled with crystals. Less common varieties of quartz include the orange citrine, which is formed by applying intense heat and pressure to amethyst. There are even combinations of quartz variants, such as a purple and orange hybrid known as ametrine.
POSITION ON THE MOHS SCALE
The Mohs Hardness Scale is a rough measure of a mineral’s hardness, determined by the mineral’s resistance to abrasion by a substance of a known hardness. The higher the number, the more resistant the mineral is to scratching or abrasion. Quartz is a 7 on the Mohs scale.
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Quizbowl is about learning, not rote memorization, so we encourage you to use this as a springboard for further reading rather than as an endpoint. Here are a few things to check out:
Amethyst has long been valued for its beauty, but the ancient Greeks believed it offered other benefits as well.
Check out this website for a more comprehensive list of quartz varieties than we can cover here.
If you’re interested in mineralogy more broadly, this video exploring how gemstones form is a good place to start.
Quartz’s piezoelectric properties make it a favorite of DIY Musicians!
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