Quartz is one of the most common minerals in the Earth's continental crust.
The term "racism" is usually applied to the dominant group in such a society, because that group typically has the means to oppress others.
One of the earliest uses for this property of quartz was in making the pickup for a phonograph.
Today, one of the most ubiquitous uses of quartz, based on its piezoelectric property, is to make "crystal oscillators" (often simply called "quartzes").
On the other hand, the presence of "impurities" (small amounts of other substances) generates many varieties of quartz, including agate, amethyst, carnelian, chrysoprase, flint, jasper, onyx, rock crystal, smoky quartz, and tiger's eye.
Quartz occurs in hydrothermal veins (veins produced through hot water circulation) and pegmatites (coarse-grained igneous rocks).
Natural quartz is often "twinned"—that is, two crystals intergrow and share some of their lattice points.
The study of quartz by Nicolas Steno (1638–1686) paved the way for modern crystallography.
Eugene Shoemaker (1928–1997) found shocked quartz in the Barringer Crater (near Winslow, Arizona) and concluded that it was produced by the impact of a meteorite.
Lechatelierite is an amorphous silica glass, which is formed by lightning strikes in quartz sand.
Today, quartz crystals are commonly used to make "oscillators" that keep track of time in wristwatches, provide a stable clock signal for digital integrated circuits, and stabilize radio transmitter frequencies.
Historically, different varieties of quartz—such as agate, amethyst, onyx, and tiger's eye—have been used as gemstones.
Not all wavelengths of light can support photosynthesis.
A quartz crystal has a property known as piezoelectricity—which means that when mechanical stress is put on the crystal, or when the crystal is made to vibrate, it produces electricity.
Pure quartz is made of crystallized silica (silicon dioxide, SiO2), but in nature it occurs in many varieties based on the presence of small amounts of other substances.
A quartz crystal oscillator is an electronic circuit in which the mechanical resonance of a vibrating quartz crystal creates an electrical signal with a precise frequency.
A transparent form is made by melting pure, naturally occurring quartz crystals at around 2,000° C in an electric or gas-fueled furnace.
Quartz has a hexagonal crystal structure made of trigonal crystals of silicon dioxide (SiO2, or silica).
A quartz geode consists of a hollow rock (usually with a roughly spherical shape) containing a core lined with a bed of crystals.
The piezoelectric principle is also used in the quartz crystal microbalance, which can make highly accurate measurements of tiny changes in mass.
Quartz is a common constituent of granite, sandstone, limestone, and many other igneous, sedimentary, and metamorphic rocks.
Under intense pressure (but moderate temperature), the crystalline structure of quartz is deformed along planes inside the crystal.
Shocked quartz is also found worldwide, in a thin layer at the boundary between Cretaceous and Tertiary rocks.
Shocked quartz is a form of quartz with a microscopic structure different from that of normal quartz.
Fused quartz has nearly ideal properties for fabricating precision mirrors such as those used in telescopes.
Fused quartz, or fused silica, refers to types of glass containing primarily silica in amorphous (non-crystalline) form.
Charles B. Sawyer invented the commercial quartz crystal manufacturing process in Cleveland, Ohio.