The Quartz family includes many popular healing stones, including Amethyst, Citrine, Clear Quartz, Prasiolite, Rose Quartz and Smoky Quartz.  While these crystals may look very different to the eye, scientifically speaking they are almost identical.  The main difference is the presence of trace impurities which give the crystal its color.

Mineral Family: Tectosilicate

Chemical Composition: SiO2
Cleavage: None
Color: Colorless and all colors
Crystal System: Hexagonal/trigonal
Form/Habit: Prismatic
Fracture: Conchoidal
Gravity:  2.7
Hardness: 7
Luminescence: Pale yellow, white, or blue (short and long wave)
Luster: Vitreous
Streak: White
Transparency: Translucent to opaque

Where does Quartz come from?

Quartz Placeholder
Quartz

Quartz is found throughout the world.  Here are a few of the deposits of interest for the metaphysical and collectors’ market:

  • Amethyst – Brazil, Canada, India, Madagascar, Mexico, Namibia, Russia, South Africa, Uruguay, United States, Zambia
  • Ametrine – Bolvia
  • Citrine – Brazil, Russia, Zambia
  • Clear Quartz / Rock Crystal – Austria, Brazil, France, Germany, India, Madagascar, Switzerland, United States
  • Prasiolite – Brazil, Canada, Poland
  • Rose Quartz – Brazil, Madagascar, Namibia, United States
  • Smoky Quartz – Australia, Brazil, Canada, Ghana, Hungary, India, Madagascar, Mozambique, Slovakia, Sweden, Switzerland, United Kingdom, United States

What is Quartz?

Quartz is a group of macro-crystalline Silicate minerals which can be colorless or appear in every shade of the rainbow.  The most famous varieties of Quartz are Amethyst (purple), Ametrine (purple and yellow),  Citrine (yellow), Clear Quartz (colorless). Prasiolite (green) Rose Quartz (pink), and Smoky Quartz (grey, brown, or black).

Scientifically speaking, a true quartz should be transparent or translucent, while an opaque version is micro-crystalline and more accurately termed a Chalcedony. However, in common practice, names like Quartz, Chalcedony, Agate and Jasper are often used loosely and interchangeably.  For example, an opaque white quartz may be called Snow Quartz, Milky Quartz, Quartzite or White Chalcedony.  By contrast, purple quartz  and pink quartz will almost always be called Amethyst and Rose Quartz, regardless of whether the stone is transparent or opaque.

Silicate minerals are the largest family of minerals, including more than 25% of all known minerals and 40% of all common minerals. In addition to being a major part of the Earth’s crust, silicate minerals have also been found on the moon and in meteorites. Silicates are minerals which contain the elements silicon (a light gray shiny metal) and oxygen (a colorless gas). Together, these two elements form a tetrahedra – a shape similar to a pyramid – with a silicon atom in the center and oxygen atoms at each of the three corners. These tetrahedra connect with other chemical structures, in six different ways, to form a wide variety of minerals and rocks.  There are six main groups of silicate minerals, and these main groups are further subdivided into secondary subdivisions, such as Quartz and Feldspar.  The Quartz family includes all varieties of Quartz, as well as Agate, Aventurine, Chalcedony, Jasper Opal, and Tiger’s Eye.

How is Quartz formed?

Quartz crystals are created when liquid magma from a volcanic eruption cools down and transforms into igneous rocks. During this cooling down period, silica acid bubbles shift from being a gas/liquid into a solid compound. The bubble becomes a hollow space in the igneous rock and the silica acid becomes Quartz crystals.  Once the Quartz has formed, a large hollow is often called a “druze,” while a smaller hollow is a “geode.”  These druze and geodes can be removed from the host rock and then split open to revel the crystals inside.

If no trace elements are present to change its color, the silic acid becomes Clear Quartz.  If trace minerals are present, then the color changes.  For example, Amethyst, Citrine, and Prasiolite typically all get their color from trace particles of iron heated to different temperatures.  While Rose Quartz’s color can be caused by iron, manganese or titanium.

How is Quartz mined?

Quartz is found all over the world and may be a primary or secondary mineral in a mining operation.  In most cases, Amethyst is the only variety that is valuable enough to justify a larger-scale mine.  Other quartz varieties are typically  mined in tandem with other precious metals and minerals, but by themselves wouldn’t be valuable enough to justify the work.  For example, many Gold mines also extract a sizeable amount of Clear Quartz.  Likewise, an Amethyst mine may be focused on the purple gem, but will also produce Citrine and Smoky Quartz.  Generally, the Quartz is found in its primary location still associated with its igneous rock matrix. But occasionally,

Artisanal mines are small-scale mines and may focus on any variety of quartz.  For example, there is a famous small-scale mine in Arkansas which produces exceptional Clear Quartz.  Likewise there are many artisanal pit mines in Madagascar that produce Rose Quartz.

Quartz Associates

Quartz minerals are associated with all other quartz varieties, including microcrystalline varieties such as Agate, Chalcedony, and Jasper.  They are also commonly associated with Calcite, Fluorite, Hematite, Muscovite, Pyrite, Rutile, Spessartine Garnet, Topaz, and Tourmaline.

Natural Quartz vs Heat Treated Quartz

Much of the Quartz on the market is natural and enhanced only by cutting and polishing. The most desirable varieties are transparent, either clear as glass or with attractive prisms that sparkle in the light and cast rainbows.  High quality Quartz is colorless or has a vivid color, while low quality is pale, dull and unremarkable.

Heat-treatments are common for Amethyst, Citrine, Prasiolite and Smoky Quartz.  Heat-treatments mimic natural processes, by heating the quartz to a high temperature much as might happen if the Quartz was near a geothermal source.  As the quartz heats, trace impurities begin to alter on an atomic level, with ions gaining and losing electrons, and the result is a change in color.  By controlling the temperature, a low-grade Amethyst can be transformed into high grade Amethyst, Citrine or Prasiolite.  All three of these crystals have iron impurities, the only difference is the heat level.  Smoky Quartz has trace impurities of aluminum, instead of iron.  The aluminum is affected by natural irradiation inside the earth, giving the quartz its smoky brown or grey coloring.  Low-grade Smoky Quartz can be exposed to radium or x-rays to produce a more valuable vivid shade.

These heat-treatments can be done at a lapidary or even directly at the mine.  From a scientific perspective, there is no way to distinguish between between naturally vivid and heat-treated crystals.  But, if you know where the crystal came from, it is possible to make an educated guess.  For example, Australia is known for having natural Smoky Quartz that are so dark they are almost black, so a Smoky Quartz from that country is more likely to be natural.

What’s the deal with all the Quartz names?

There are countless marketing names given to transparent and opaque Quartz minerals.  For example, a Clear Quartz with Hematite inclusions may be called “Hematite Quartz,” “Scarlet Quartz,” “Strawberry Quartz,” “Tangerine Quartz,” “Elestial Quartz,” etc.  There are no standard rules that govern marketing names.  The most useful marketing names are those that indicate a specific deposit or specific inclusions.  For example,  Auralite 23, is a Quartz mineral that combines Amethyst with up to 22 other minerals and comes from a small deposit in Ontario, Canada.  By contrast, Super Seven, is a Quartz mineral that combines Amethyst with up to 6 other minerals, and comes from a variety of small mines in Minas Giras, Brazil. 

Some marketing names are purposefully obscure and target the healing crystal community, promising a rare stone with high-energy.  In reality, these are typically lower-grade stones.  For example, Azeztulite  is a common opaque quartz that is not associated with any single location.  It’s high price is justified solely by its purported energy and a story involving angelic beings.  Likewise, “Green Amethyst” is often used in place of Prasiolite, because the name recognition helps drive the price up.  In the USA, it against the Federal Trade Commission Guidelines to call Prasiolite “Green Amethyst,” nevertheless the practice is very common among wholesalers and retailers alike.