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Quartz vs. Opal: What's the Difference?

Edited by Aimie Carlson || By Harlon Moss || Updated on November 7, 2023
Quartz is a hard, crystalline mineral composed of silicon dioxide, while opal is a hydrated amorphous form of silica with a play of color.

Key Differences

Quartz is a widely available mineral, known for its durability and range of colors, from clear to black. Opal is prized for its unique display of rainbow-like colors, known as opalescence, which is not found in quartz.
The crystalline structure of quartz results in its glass-like luster and clarity, which can be consistent throughout the stone. Opal’s amorphous structure scatters light to create its characteristic iridescent hues, which vary in each specimen.
Quartz, used in jewelry and electronics, is valued for its piezoelectric properties, whereas opal is mainly used in jewelry for its aesthetic appeal and does not have industrial applications like quartz.
The formation of quartz occurs within a wide range of geological environments, which is much broader than the specific conditions required for opal formation, typically near hot springs or in sedimentary rocks.
In terms of care, quartz is easier to maintain due to its hardness, ranking 7 on the Mohs scale, while opal, being more delicate with a Mohs hardness of 5.5 to 6, requires careful handling to avoid scratching.

Comparison Chart


Crystalline silicon dioxide
Hydrated amorphous silica


Glass-like luster, transparent to opaque
Iridescent play of color

Hardness (Mohs Scale)

5.5 to 6


Jewelry, electronics, timepieces
Mainly jewelry

Formation Environment

Wide range of geological settings
Near hot springs, sedimentary rocks

Quartz and Opal Definitions


A mineral used in making jewelry, known for its durability.
Her favorite necklace featured a rose quartz pendant.


A hydrated form of silica that is classified as a mineraloid.
Unlike the rigid structure of crystals, opal has an amorphous form.


A hard, crystalline mineral composed of silicon dioxide.
The quartz crystals were found in the cave's deepest chamber.


A precious stone often associated with luck and magic in folklore.
In medieval times, opal was considered a stone that could provide great luck.


A term used for a variety of gemstones based on color variations.
Smoky quartz has a distinctive brown translucence.


A gemstone known for its flashing rainbow colors or “play of color”.
The opal ring she wore sparkled with every hue under the sun.


A common mineral found in the Earth's crust.
Granite rock is composed of feldspar, mica, and quartz.


A gem that can display a phenomenon known as opalescence.
The opalescence of this opal is particularly vibrant, showing a spectrum of colors.


A piezoelectric material utilized in watches and electronic devices.
The quartz movement in his watch was incredibly precise.


A birthstone for the month of October.
As a birthday gift, he chose an opal, the October birthstone, for its unique beauty.


A very hard mineral composed of silica, SiO2, found worldwide in many different types of rocks, including sandstone and granite. Varieties of quartz include agate, chalcedony, chert, flint, opal, and rock crystal.


A mineral of hydrated silica.


(mineral) The most abundant mineral on the earth's surface, of chemical composition silicon dioxide, SiO2. It occurs in a variety of forms, both crystalline and amorphous. Found in every environment.


A gemstone made of this mineral, noted for its rich iridescence.


Crystal meth: methamphetamine hydrochloride.


A form of silica, or silicon dioxide (SiO2), occurring in hexagonal crystals, which are commonly colorless and transparent, but sometimes also yellow, brown, purple, green, and of other colors; also in cryptocrystalline massive forms varying in color and degree of transparency, being sometimes opaque.


Colorless glass made of almost pure silica


A hard glossy mineral consisting of silicon dioxide in crystal form; present in most rocks (especially sandstone and granite); yellow sand is quartz with iron oxide impurities


What is quartz?

A common crystalline mineral made of silicon dioxide used in various applications.

Is opal a crystal?

No, opal does not have a crystalline structure; it's amorphous.

How is quartz formed?

From the cooling of magma or in hydrothermal veins.

What characterizes an opal?

Opal is distinguished by its unique play of color and mineraloid status.

What are the uses of quartz?

Jewelry, electronics, and as a timekeeping element in watches.

Is quartz durable?

Yes, it is very durable with a Mohs hardness of 7.

Can quartz be colored?

Yes, impurities can give quartz various colors, from purple to black.

Why is opal precious?

Its rarity and the unique play of color make opal a coveted gemstone.

What is the difference between precious and common opal?

Precious opal shows a play of color, while common opal does not.

Are all opals colorful?

Most opals show a play of color, but some may be milky or dull.

How should opal jewelry be cared for?

Opal should be cleaned gently and kept away from harsh chemicals and environments.

Is quartz affected by chemicals?

Quartz is chemically inert and resistant to most acids.

Is opal a good investment?

High-quality opals can be a good investment, but they require knowledge and care.

What is the source of opal's colors?

The diffraction of light through its silica spheres causes the colors.

Can opal be used in everyday jewelry?

Opal is softer and requires careful handling, making it less suited for daily wear.

Does quartz have any metaphysical properties?

Some believe quartz has healing and energy-amplifying properties.

Why is quartz used in electronic devices?

Because of its piezoelectric properties, which can generate an electric charge under pressure.

What factors affect opal's value?

Color range, intensity, pattern, and brightness are key value factors.

Can quartz scratch easily?

No, it's scratch-resistant due to its hardness.

What are the different types of quartz?

There are many types, including amethyst, citrine, and rose quartz, categorized by color.
About Author
Written by
Harlon Moss
Harlon is a seasoned quality moderator and accomplished content writer for Difference Wiki. An alumnus of the prestigious University of California, he earned his degree in Computer Science. Leveraging his academic background, Harlon brings a meticulous and informed perspective to his work, ensuring content accuracy and excellence.
Edited by
Aimie Carlson
Aimie Carlson, holding a master's degree in English literature, is a fervent English language enthusiast. She lends her writing talents to Difference Wiki, a prominent website that specializes in comparisons, offering readers insightful analyses that both captivate and inform.

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