Quartz is the most abundant and widespread mineral found on the Earth’s surface, and is found in all parts of the world. It forms at all temperatures. It is found in magmatic, metamorphic and sedimentary rocks. It is highly resistant to both mechanical and chemical weathering. This durability makes it the dominant mineral of mountain tops and the main element found in beach, river and desert sand.
Quartz is one of the most common and varied minerals on earth, and its abundant colours produce many types of gemstones. Amethyst and citrine are the most popular and valuable types of quartz. Chalcedony describes any form of quartz that is microcrystalline, in compact form, with no visible crystals. Coloured varieties of chalcedony have different names, such as agate, carneol (reddish-brown), tiger’s eye (yellow-brown) and chrysoprase (light green). Most commonly, quartz varieties are treated as different stones and each has its own characteristics for which they are chosen in the fascinating world of jewellery.
Pure quartz, also known as rock crystal, is colourless. Various impurities present in quartz rock are responsible for the extensive color palette of this stone. The main types of crystalline quartz known and used as semi-precious stones are as follows:
Amethyst
Amethyst is the most popular and valuable quartz gemstone. Amethyst ranges in color from light purple to dark purple.
Citrine
Citrine is found in shades of yellow, orange or reddish-brown. It is usually coloured by heat treatment with amethyst or smoky quartz. Light yellow or lemon yellow in colour, citrine is often called Lemon Quartz in the natural stone field.
Smoky Quartz
Smoky quartz is the brown, “smoky” variety of quartz. It ranges in color from light brown to black. Despite its dark color, it is rarely opaque.
Pink quartz
Its colour ranges from light pink to medium pink. Rose quartz is often milky or cloudy and can lack good transparency.
PANTONE® Color Institute, the company that declares the color of the year, named Rose Quartz as its “Color of the Year” in 2016.
Rock Crystal
The colourless and transparent variety of quartz, free of any impurities, is known by this name. Impeccable and very large cuts can be made with this stone.
Milky quartz
Milky Quartz is the white, translucent to opaque variety of quartz. Although it is very common in nature, it is not used as a gemstone.
Rutilated Quartz
Colorless quartz with inclusions of golden-yellow rutile with fine inserts is known as rutilated quartz.
Amethyst
The name comes from the name of the two stones of which it is composed: amethyst + citrine. Ametrine is an interesting combination of colors, namely purple amethyst and yellow-brown citrine.
Prasiolite or green quartz
Prasiolite or green quartz has a light green colour obtained by heat-treating certain types of amethyst. It may also be called “green amethyst” by some jewellers.
Blue quartz
The blue variety of quartz that is common in nature is rarely used as a gemstone.
Tourmaline quartz
Colourless quartz with tourmaline inclusions, often in the form of long, thin black crystals, is known as “tourmaline quartz”.
Cat’s eye quartz
Cat’s eye quartz is a quartz with dense and small inclusions of rutile, which creates the effect of a cat’s eye. It is usually grey in colour and translucent.
Origins and legends
The name quartz comes from the Greek, “krystallos”, which means ice. Because quartz is such a well-known crystal, cultures around the world have their own mythology related to this stone. Ancient Greek philosophers such as Theophrastus believed that transparent stone was a form of permanent ice, so cold that it could not thaw.
People in ancient times believed in the magical powers of quartz. Medieval seers used crystal balls made of colourless quartz because it was said to help predict the future. Ancient Roman, Egyptian and Greek civilisations used quartz crystals as powerful talismans. The Romans used rose quartz as a seal to signify ownership, and the Egyptians believed the stone could prevent aging.
Quartz is extremely common and is found in many localities around the world. The major sources are far too numerous to mention, although in general the most prolific countries producing quartz gemstones are Brazil, Madagascar, India and the USA (Arkansas).
The Assyrians, along with the Romans, were among the first to use this stone in jewellery. Rose quartz jewellery was found around 800-600 BC in the area once known as Mesopotamia (modern-day Iraq) and is believed to have been worked by the Assyrians.
Technical characteristics of quartz
Quartz is one of the most useful natural rocks. It is a chemical compound consisting of one part silicon and two parts oxygen (silicon dioxide (SiO2)). Its usefulness can be linked to its physical and chemical properties. It has a hardness of 7 on the Mohs scale, which makes it very hard. It is chemically inert in contact with most substances. It has electrical properties and heat resistance that make it valuable in electronic products. Its luster, color and diaphanousness make it useful as a stone for jewelry and also in glass making.
Quartz is also an unusual mineral. It is stable below 573 degrees Celsius, but between 573 and 870 degrees, tridymite (another silicon mineral) forms. At 1470 degrees, tridymite undergoes a structural rearrangement and becomes cristobalite, which is isometric. At 1710 degrees, cristobalite melts to a viscous liquid. If it is cooled rapidly, silicon glass forms.
Chemical formula: SiO2
Color: white, colorless, blue, red, green, yellow, orange, brown, pink, purple, grey, black, multicolored
Mohs hardness: 7
Crystal system: hexagonal
Refractive index: 1.54 – 1.55
Transparency: transparent to translucent
Gloss: vitreous
Mineral class: quartz
Quartz is one of the first widely cultivated gemstones. The major development was made during the Second World War to provide crystals for radio sets. Today, our computer industry relies on synthetic quartz. Not because there is a shortage of natural crystals, but synthetics are always clean and less time consuming to cut into the necessary pieces.
Quartz is mainly grown in pegmatite, but it is also grown hydrothermally in laboratories. It can grow to very large sizes, reaching thousands of carats. Exceptions are amethyst, which can rarely be cultured and is found in stones exceeding 100 carats, and rose quartz, which can rarely exceed 30 carats. Translucent examples of quartz can weigh several kilograms.
Energetic and spiritual properties
The significance of colorless or transparent quartz is known for its high vibrations. Clearing your mind, body and spirit of any clutter, a clear quartz crystal can help you align with your highest self and live to your highest potential.
In the Middle Ages, physicians used quartz in their healing potions. Early American cultures used quartz amulets. Known as the “love stone,” it was said to balance emotions and heal anger and disappointment.
In South America, native cultures believed that those transparent crystal quartz skulls held the spirits of their ancestors. And in ancient Egypt, clear quartz crystal was used to build monuments because it was believed that they channeled energy from the planetary system. And in ancient Japanese mythology, clear quartz crystal stone was considered a symbol of perfection, as it was believed to be the physical form of a white dragon’s breath. Mythology held that dragons were symbols of generosity and kindness, so the crystal became associated with such values as well.
Quartz care tips
To clean quartz jewellery, use warm water, detergent and a soft brush. We do not recommend using steam;
Keep jewellery in the dark, away from sunlight or other UV light sources, to preserve its color (in a jewellery box);
Another way to clean and charge a quartz is to have it exposed to full moonlight. It is recommended to place quartz jewelry in direct moonlight, either outside or on a window sill.