A Complete Guide to the Quartz Mineral Family

This article serves as part of an ongoing series of profiles on the different varieties of precious & semi-precious gemstones. To view the entire list, click here.

The quartz family of minerals is among the most interesting and varied groups of gemstones found on Earth. From the bright purple colors of amethyst to the deep, smoky browns of smoky quartz, this mineral family occurs in many different colors and varieties that have appealed to humanity for aeons. Quartz is valued not just for its beauty but also for its special physical traits and uses in various industries. In this guide, we'll explore how quartz forms, where it is found, its colors, inside details, treatments, and how to judge its quality. We'll also look at what astrology says about quartz and how much it costs. Here is everything you need to know about the quartz mineral family.

1. Quartz - Formation & Occurrence

Quartz is a mineral made of silicon and oxygen (silicon dioxide, SiO₂). It is one of the most abundant minerals found in the Earth's crust. Its formation is a complicated process that can happen in several geological ways. One of the most common is when silica separates from hot watery solutions, resulting in the growth of quartz in cracks or hollow spaces in rocks. Quartz can also form through the changing of silica-rich rocks or the eroding and re-depositing of existing quartz grains. Sometimes confused with feldspar, quartz and feldspar are actually different minerals with distinct properties of hardness. Quartz can also form when existing silica-rich rocks like chert or sandstone are exposed to high heat and pressure, causing recrystallization into new quartz grains and crystals – sometime also forming quartzites. Some of the largest, well-formed quartz crystals grow in pegmatites - igneous rocks formed from silica-rich magmatic fluids. As pegmatites cool very slowly, it allows time for quartz to crystallize into bigger crystals.

Rough Clear Quartz

Quartz minerals can be found in various geological settings around the world. Rock crystal or clear quartz, a colorless and see-through variety of this mineral, is commonly found in igneous and metamorphic rocks, as well as in pegmatite veins. Amethyst, the purple variety of quartz is often associated with volcanic rocks and can be found in geodes and vugs (hollow spaces within rocks). Smoky quartz is common in pegmatites and hydrothermal veins, while citrine is typically found in volcanic environments or is made by heat-treating amethyst.

Factors that promote quartz crystal growth include silicate-rich fluids, slow cooling rates, open spaces like cracks and cavities, and chemically active solutions delivering silica. At normal temperatures, quartz forms trigonal (three-sided) crystals made up of interlocked silicon-oxygen tetrahedral units. Above 573°C, it transforms into a hexagonal crystal structure. Other ways quartz forms include precipitation in geodes, growth along hydrothermal veins, and crystallization from volcanic magmatic fluids.

2. Where Are Quartz Minerals Found?

Quartz is among the most common minerals and is found all over the globe, but certain varieties come from specific regions. Amethyst, the purple variety of quartz, is sourced mainly from Russia, Sri Lanka, Brazil, Uruguay, Mexico, Namibia, and parts of the United States and India. Citrine is mined in Brazil, Spain, Mexico, Madagascar, Russia, and some U.S. states like California. Rose quartz deposits exist in Brazil, India, Madagascar, South Africa, Germany, and states like South Dakota. Smoky quartz comes from Scotland, Switzerland, Brazil, Canada, and U.S. states like Arkansas and Colorado. Clear rock crystal quartz is found in Brazil, Madagascar, Mexico, the U.S., Russia, Switzerland, and Japan. While quartz forms in many environments, these locations are well-known for their high-quality deposits of these popular quartz varieties. Agate, which is the banded variety of chalcedony (composed of quartz and moganite) is also found throughout the world.

3. The Colour Span of Quartz

Quartz occurs in many different colors, which are grouped into specific "varieties." The color depends on the trace elements and inclusions present in the quartz crystal structure. Here are some of the common-coloured varieties of quartz gems:


• Purple Quartz - Amethyst: The deep purple color comes from iron inclusions and exposure to natural radiation.
• Yellow Quartz - Citrine: The yellow-to-orange hue is caused by iron impurities. Some citrine is made by heat-treating amethyst.
• Pink Quartz - Rose Quartz: The pretty pink shade comes from tiny amounts of titanium, iron or manganese.
• Grey Quartz - Smoky Quartz: Shades from light gray to charcoal black form from radiation altering aluminum impurities.
• Green Quartz - Prasiolite: A rare green color caused by natural heat treatment altering the quartz ingredients.
• Colorless Quartz - Clear Quartz: Pure quartz with very few impurities looks completely transparent and clear like glass.
• Purple & Yellow Quartz - Ametrine: This unique variety shows both purple and yellow colors in the same crystal due to different iron elements.

So while plain quartz is colorless, the addition of various trace elements during its formation creates this gorgeous rainbow of quartz colors found in nature.

Quartz minerals occur in a plethora of colors

4. Common Inclusions in Quartz

Inclusions are foreign materials trapped inside the crystal structure of quartz during its formation. These inclusions can add to the beauty and uniqueness of each quartz specimen. Some common solid inclusions found in quartz include:


• Rutile Needles: Thin, hair-like needles of the rutile mineral that create a stunning visual effect.
• Actinolite: Green, fibrous crystals of the actinolite mineral which results in a unique feathery pattern within the quartz.
• Chlorite: Green, flaky inclusions of the chlorite mineral to add a distinctive visual texture.
• Hematite Platelets: Flat, hexagonal platelets of the hematite mineral that give a reddish-brown color to the quartz.
• Pyrite: Brassy yellow cubic crystals of the pyrite mineral, often referred to as "fool's gold," lending a metallic appearance to the quartz.
• Negative Crystals: Negative quartz crystals form when the growth pattern leaves an imprint or hollow space in the shape of a crystal inside the quartz. Common examples are negative hexagonal pyramids.
• Bubbles: Scientists determine inclusions in quartz by heating the crystal until bubbles or fluid inside exsolve or disappear. Some quartz minerals are completely filled with trapped gas and liquid inclusions, making the entire crystal structure appear white and opaque.

Rutile Needle inclusions in a rough Rose Quartz mineral

5. Common Treatments & Enhancements of Quartz

While natural quartz is highly prized, some varieties may go through treatments or enhancements to improve their appearance or durability. Common treatments of Quartz include:


• Heat Treatment/Thermal Enhancement: Heating amethyst (purple quartz) can turn it yellow or orange, creating citrine. This is one of the most common heat treatments. Heating smoky quartz can remove the smoky brown color, giving a clear or yellowish quartz. Some rose quartz gets its pink color from heat treatment of paler quartz.
• Irradiation: Most natural smoky quartz gets its brown/gray color from natural radiation exposure over time. Man-made irradiation can artificially create this coloring. Irradiating clear quartz can produce yellow, green or black quartz depending on the radiation type and intensity.
• Dyeing & Coating: Lower-quality quartz may be dyed intense colors like purple, blue or green that don't occur naturally. A thin metallic coating can give quartz an iridescent or multi-colored finish.
• Fracture-Filling: Transparent fillers like glass or plastic resins can fill cracks and cavities in cloudy or fractured quartz, improving clarity. This makes the quartz more durable and gives a glass-like luster, though it can look unnatural up close.

Heating Amethyst often results in the formation of a Citrine (Source: Hibiscus Moon)

Quartz Minerals - A Quick Snapshot

6. Evaluating the Quality of a Quartz Mineral

Quartz gemstones are renowned for their transparency and vivid colors. To evaluate the quality and value of a quartz gem, it makes sense to consider the 4Cs framework:

• Color: For colored varieties like amethyst and citrine, the richness, deepness, and evenness of the color matter a lot. Specimens with bold and saturated colors that are consistent throughout the gem are most valuable. Uneven or faded coloring can make the specimen less desirable.
• Clarity: How clear and transparent the quartz is affects its quality. While some inclusions (inside details) can add visual interest, too many or unattractive trapped materials lower the value. In general, clearer quartz with minimal inclusions is preferred.
• Cut: For quartz gemstones, the quality of the cutting and shaping is crucial. A well-executed cut maximizes the stone's sparkle and beauty, while a poor cut can make it look dull. Symmetry and polish are also important.
• Carat Weight: Larger, bigger quartz gemstones tend to be rarer and more valuable, especially for uncommon varieties. Sizeable, nicely-formed specimens are highly prized.

7. How Much Does Quartz Cost?

The cost of quartz minerals can vary a lot depending on the variety, quality, and rarity. Common varieties like clear quartz, citrine, and smoky quartz can be relatively inexpensive. Rarer and more valuable varieties like fine amethyst and high-quality citrine such as Madeira citrine can cost more for exceptional specimens.

8. Quartz in Astrology

Different varieties of quartz are believed to possess unique metaphysical properties and energetic associations. For example, amethyst is known for its calming and spiritually awakening abilities which help to promote peace, balance and higher consciousness. Citrine is said to be a stone of optimism, creativity and self-confidence. Rose quartz resonates with unconditional love, self-love and emotional healing. Astrologically, these different quartz types are thought to align with and enhance the personalities and energies of the various zodiac signs.

In general, quartz is revered in spiritual practices and crystal healing for its ability to amplify energies, promote balance and clarity, and purify the mind and body of negative vibrations. Quartz is said to amplify intentions during meditation, remove energy blockages, and facilitate concentration and mental focus. The pure, universal life-force energy of quartz is believed by many to have profound healing potential, both physically and psychologically, depending on the variety used.

The quartz family is truly a wonder of nature, showing a remarkable diversity of colors, forms, and properties. From the brilliant purple hues of amethyst to the deep, smoky tones of smoky quartz, each variety holds its own unique beauty and meaning. Whether used in jewelry, spiritual practices, or industrial applications, quartz continues to fascinate and inspire people around the world. With its abundance and versatility, the quartz family will undoubtedly continue to be a treasured part of our Earth's natural wonders for generations to come.