Quartz is one of the most abundant minerals on earth and comes in a wide variety of forms. From clear quartz to the deep purples of amethyst, this gem has the power to dazzle throughout the spectrum of the rainbow. Other crystals like calcite and apophyllite can even be mistaken for quartz, so read on to learn the difference between quartz and other crystals!
What Makes A Quartz Crystal?
Quartz is composed mainly of silicon dioxide and in its purest form will form into a clear hexagonal crystal with pyramidal ends. Other elements such as inclusions, mineral impurities, heat, and natural irradiation from the surrounding rocks will add features and color to individual stones giving us many wonderful varieties, from the milky whites of chalcedony to the golden yellows of citrine.
When a silicon atom combines with two oxygen atoms they form a single molecule of silicon dioxide, the chemical composition of quartz. The crystals then form into the distinctive hexagonal shape and tend to be mostly transparent with a Mohs mineral hardness rating of 7. This makes it a relatively hard gem and quite suitable for jewelry as it is quite resistant to impact and other types of wear and tear.
Where there are impurities in the crystal due to geological conditions, the color of the stone may alter giving rise to variants such as rose quartz, amethyst, citrine, chalcedony, smoky quartz, and others.
Quartz crystals can generally be divided into either macrocrystalline or cryptocrystalline. Macrocrystalline gems, such as amethyst, contain crystals that are easily visible to the naked eye, while cryptocrystallines, such as chalcedony, require magnification to see the crystals.
Top 5 Different Kinds of Quartz
Here are our top 5 picks of gorgeous quartz gemstones and why they differ from clear quartz. We've also added in a couple of crystals that although not quartz, are commonly mistaken for it.
Difference Between Quartz and Citrine
This wonderful stone ranges in color from pale yellow to a satisfying translucent brown. In its natural form, citrine is quite a rare stone, so you need to check before you make a purchase that the color hasn't been added artificially by a heating process.
The color change occurs due to the presence of submicroscopic iron particles within the silicon dioxide. Depending upon the density of these impurities the crystal will have anything from a light yellow to an attractive rusty-brown appearance.
These colors can be replicated with heat treatments, but the process will leave fine lines in the crystal. The natural variety will tend to have a more cloudy appearance than the artificial evenness of a heat-treated stone.
Difference Between Quartz and Smoky Quartz
Sometimes marketed as 'smoky topaz', this stone needs no subterfuge to make it more attractive. The beautiful smoky effect occurs when the rock in which the quartz is embedded emits natural radiation that activates aluminum impurities within the crystal.
Depending upon the radiation strength and the density of the aluminum, the colors of smoky quartz range from almost completely transparent grays to brown or even black opacity.
Although topaz may also have this smoky effect it is a different stone with a Mohs hardness rating of 8 compared to quartz’s 7. As such it is a more durable stone and more valuable than a typical quartz gem. If you are going to pay for a ‘smoky topaz’ stone, make sure it really is topaz before you make your purchase.
Difference Between Quartz and Rose Quartz
Rose quartz ranges from pale, delicate pink to seductively deep rose-red hues. This variant gains its color through the presence of either iron, manganese, or titanium impurities within the crystal. Typically rose quartz does not form as a cluster unlike most of the quartz family, with the exception of a rare 'crystalized rose quartz' from Brazil (shown here).
Depending upon the nature and density of the trace elements the depth of color will change. This particular color range tends to be very stable and will resist fading due to sunlight or heat.
Some of the rarer types of pink-tinged quartz stones will have elements of aluminum or phosphate and their colors are more highly valued. If you are paying more for a rose quartz stone this may be the reason why, but be sure to ask your vendor if this is the case.
Difference Between Quartz and Amethyst
Everyone's favorite purple gemstone! The amethyst is another variation of the quartz crystal family. In the same way that the colors of smoky quartz form through the interaction of impurities in the crystal with natural background radiation, amethyst also depends upon this process to create the wonderful colors that make it so famous.
After the initial crystallization of the quartz, gamma rays emitted from the host rock cause iron impurities to acquire those beautiful purple shades. The hues produced by this interaction vary from eye-catching bright violets to the more demure shades of lavender.
The range of color may also vary from one area of the crystal to another giving rise to the effect of 'color zoning'. Where the trace iron impurities are denser the color will be more intense.
*Fun fact, sometimes citrine and amethyst are found together in the same crystal formations. This wonderful combination is called ametrine, so watch out for this unusual gemstone.
Difference Between Quartz and Chalcedony
The milky whites and blues of chalcedony are not what we associate with silicon dioxide crystals and yet, this gem is also a part of the quartz family.
While most quartz gemstones fall into the macrocrystalline category, chalcedony is cryptocrystalline, meaning that the its crystalline structure is not visible to the naked eye. The stone needs to be thinly sliced and viewed under a microscope in order to see the crystals.
The quartz content in chalcedony is mixed with moganite. This combination of crystal and stone creates an opaque gem with beautiful bands of contrasting colors and flowing patterns.
Other examples of this category of mixed crystal and stone, include onyx, jasper, agate, and carnelian, to name a few.
An advantage of this cryptocrystalline structure is that the stone is less likely to fracture and is ideal for jewelers to work with when creating unique or custom items.
Pure chalcedony without any trace impurities has a beautiful chalky white color and is sometimes referred to as ‘milky’ quartz.
The other most common color associated with chalcedony is blue. This variety is more highly valued, particularly if the color saturation is more complete.
Another name for this stone is gem silica and the color derives from the presence of copper deposits. The interaction between the silicon dioxide and the metal causes the crystal to take on its characteristic shades of blue.
Chalcedony often mixes with quartz as well to create the beautiful banding you see in most agates.
Difference Between Quartz and Calcite
This is the first stone on our list that doesn’t belong to the quartz family. We include it here because it is often confused for quartz although it is fundamentally different and resembles it only superficially.
Calcite is composed of calcium carbonate, more specifically CaCo3, or one calcium to three carbon atoms. Unlike the hexagonal shape of quartz, it forms into scalohedrons, rhombohedrons, and a variety of other shapes.
Calcite in its purest form is transparent, just like clear quartz. As a result of impurities, it can also be found in white, black, red, brown, yellow, orange, gray, and even occasionally, in blue varieties.
Where quartz is one of the harder minerals at 7 on the Mohs scale, calcite is much softer, coming in at 3. While the resemblance to quartz may in some cases be quite remarkable, the similarity is superficial.
Difference Between Quartz and Apophyllite
This is another stone that can be easily confused with quartz, although, like calcite, it belongs to an entirely different family.
Typically transparent, its chemical composition is potassium calcium silicate and it forms into wonderful cubic and pyramidal structures.
The name apophyllite comes from the Greek term ‘apophyllos’ which means ‘to flake off in leaves’. This describes its property of peeling apart under exposure to heat which causes it to lose its natural water content.
This fascinating stone comes in white, pink, yellow, brown, violet, green, and transparent varieties. It may also be opaque under some circumstances. The most common type is transparent, leading to confusion with clear quartz.
Now that you know the difference between the main types of quartz crystal, you can hopefully shop for crystals with more confidence!