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What Is Quartz? Clear Quartz and the Quartz Family

By Digital Towns Crystals · Last reviewed October 7, 2026

Short answer: quartz is silicon dioxide, the second most common mineral in the Earth's crust, after feldspar. Pure quartz, called clear quartz or rock crystal, is colorless and transparent, and it grows as six-sided crystals with pointed ends. Traces of other elements, radiation and tiny inclusions create a whole family of colored quartz, including amethyst, citrine, rose quartz and smoky quartz. Quartz rates 7 on the Mohs scale, generates electricity when squeezed, and in crystal traditions is treated as an all-purpose stone.

What is quartz?

Quartz is silica, silicon dioxide (SiO2). Its atoms form a continuous framework of silicon-oxygen tetrahedra, each oxygen shared between two of them. It makes up about 12 percent of the Earth's lithosphere by mass, second only to the feldspar group. Quartz is a defining part of granite, very common in sandstone and shale, and common in metamorphic rocks such as schist, gneiss and quartzite. Because it resists weathering so well, it piles up as sand and pebbles in streams and soils.

Quartz rates 7 on the Mohs scale, has no cleavage and breaks with a smooth, curved fracture. That makes it hard and durable for jewelry, carving and handling.

Where does the name come from?

The word quartz comes from the German Quarz, used since the 14th century, which may trace back to a Slavic word meaning "hard". The ancient Greeks called it krystallos, from a word meaning "icy cold", because some philosophers, including Theophrastus, believed it was a form of ice so deeply frozen that it could never melt. That is the origin of our word crystal.

What does a quartz crystal look like?

Quartz typically grows as a six-sided prism capped by a six-sided point. Natural points grow attached to rock at one end; crystals that grew freely can be pointed at both ends, like Herkimer diamonds. Clusters of many points growing together from one base are common, and quartz crystals often line geodes.

The largest documented single quartz crystal was found near Itapore, in Goiás, Brazil. It measured about 6.1 by 1.5 by 1.5 meters and weighed over 39,000 kilograms.

What are the varieties of quartz?

Pure quartz is colorless. Its colored varieties come from impurities, natural radiation or inclusions of other minerals:

Variety Color What causes it
Clear quartz (rock crystal) Colorless No impurities
Amethyst Purple Natural irradiation and traces of iron
Citrine Yellow to orange Debated; most sold is heated amethyst
Rose quartz Pale pink Microscopic fibers of a mineral related to dumortierite
Smoky quartz Gray, brown to black Natural radiation acting on aluminum
Milky quartz White Tiny trapped bubbles of gas or liquid
Prasiolite Green Traces of iron; most is heated amethyst
Dumortierite quartz Blue Silky inclusions of blue dumortierite
Rutilated quartz Clear with gold, red or black needles Needles of rutile

The fine-grained forms of quartz are a family of their own: chalcedony, including agate and carnelian, opaque jasper, and tiger's eye. Aventurine, a glittering quartz rock, is covered in its own guide.

Phantom quartz and enhydros

  • Phantom quartz shows the ghostly outline of an earlier crystal inside a larger one. A pause in growth, a change in composition or a dusting of another mineral marks the boundary, and the crystal then keeps growing around it.
  • Fluid inclusions are tiny pockets of the liquid a crystal grew from, trapped inside it. As the crystal cools, the liquid shrinks more than the quartz, often leaving a small vapor bubble. Crystals with visible water pockets and moving bubbles are sold as "enhydro" quartz.

What is aura quartz?

Aura quartz is natural quartz coated with an ultra-thin metal film in a vacuum process, which produces vivid iridescent colors. Gold gives light blue ("Aqua Aura"), gold with platinum gives purple and silvery shades ("Angel Aura"), and indium gives dark blue. The quartz is real, but the color is a man-made coating, so aura quartz should always be sold as coated.

Why is quartz used in clocks?

Quartz is piezoelectric: squeezing a crystal produces an electric charge. Jacques and Pierre Curie discovered this in 1880. Today one of its most common uses is the quartz crystal oscillator, which keeps time in quartz watches and provides stable signals for electronics. Almost all the quartz crystal used in electronics today is synthetic, grown by the hydrothermal method, partly because natural quartz is often twinned.

Is quartz treated?

Sometimes. Heat and irradiation can induce color in some quartz: most citrine and prasiolite are heated amethyst, and some smoky quartz has been irradiated. Aura quartz is coated. Synthetic quartz is also grown for industry and occasionally for jewelry.

What is clear quartz traditionally associated with?

In modern crystal traditions, clear quartz is treated as an all-purpose stone, associated with clarity, focus and amplifying intention, and it is commonly linked with the crown chakra. Quartz crystal balls have long been used for scrying, or crystal gazing, and the scholar John Dee kept a crystal he said was given to him by an angel in 1582.

These are traditions and beliefs. In a 1999 study, people meditating with real quartz and with an identical fake reported the same sensations, which points to expectation rather than the crystal. Quartz's real, measurable powers are its hardness, clarity and piezoelectricity.

Raw, tumbled and polished quartz

Clear quartz is sold as natural points, double-terminated crystals and clusters, and polished into towers, spheres, obelisks, wands, hearts and tumbles. Milky quartz, clouded with tiny bubbles, is the most affordable. The crystal shapes guide explains how each shape is made.

How do you care for quartz?

  • Wash it with warm water and mild soap, then dry it.
  • Avoid sudden temperature changes, which can crack crystals, especially those with inclusions.
  • Protect points and edges from knocks, which can chip them.
  • Clean aura quartz gently with a soft, dry cloth rather than abrasives, to protect the thin coating.
  • Keep amethyst, smoky quartz and natural citrine out of strong sunlight, which can fade them.

How can you tell real quartz from glass?

  • Hardness: quartz, at 7, scratches glass; glass does not scratch quartz.
  • Inclusions: natural quartz often has wispy veils of fluid inclusions, fractures or other minerals inside.
  • Shape: natural points are six-sided prisms with six-sided tips.
  • Ask about synthetics: lab-grown quartz exists, though it is used mostly in industry and is less prized as a gemstone.

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Frequently asked questions

What is quartz made of?

Silicon dioxide, SiO2. It is the second most common mineral in the Earth's crust, after feldspar.

What is clear quartz?

Pure, colorless quartz, also called rock crystal. Colored varieties such as amethyst and rose quartz are the same mineral with impurities or inclusions.

What is milky quartz?

White quartz clouded by countless tiny bubbles of gas or liquid trapped as the crystal grew.

Is aura quartz natural?

The quartz is natural, but the rainbow color is a thin metal coating applied in a vacuum process. It should be sold as coated quartz.

Why is quartz used in watches?

Quartz is piezoelectric, producing an electric charge when squeezed. Quartz oscillators use that property to keep precise time.

What is clear quartz traditionally associated with?

In crystal traditions it is an all-purpose stone associated with clarity and focus, and linked with the crown chakra. These are traditional meanings rather than measurable properties.

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