Smoky Quartz: Properties, Facts and Photos

What is Smoky Quartz?

Smoky quartz is a variety of quartz distinguished by its brown to grey colour, caused by natural radiation interacting with trace impurities within the crystal structure.

It's well known for its large, translucent to transparent crystals, which are often well-formed and free from inclusions.

Smoky quartz is one of only a few black or brown minerals from which gemstones are cut. Others include black beryl, which is relatively rare, and black and brown corundum. 

Smoky quartz occurs in various shades, from pale brown and yellowish-brown to shades so deep they appear almost black. Some crystals can also be slightly grey.

The very dark brown to nearly opaque crystals are known as morion.

The name morion seems to have originated from the works of the ancient Roman author and naturalist Pliny the Elder. In his encyclopaedia, Naturalis Historia, he refers to a stone called mormorion, a dark, translucent crystal from India. It's believed that over time, the name was misread or simplified and became morion. 

Black quartz crystals found in host rocks such as gypsum, anhydrite, or limestone are sometimes mistaken for very dark smoky quartz.

The colour of smoky quartz forms when natural radiation from surrounding rock interacts with traces of aluminium within the crystal structure, causing structural changes that produce its distinctive colour.
Smoky quartz is relatively common, so it doesn't tend to be particularly expensive. That said, a considerable amount of the material being sold is clear quartz that's been heated to produce the smoky colour. The reason for doing this is because high-grade natural smoky quartz is less abundant.

Low-grade natural citrine can also be used.

Some smoky quartz will fade with prolonged exposure to UV light.  

The variety known as 'Cairngorm' is mined on Cairn Gorm, a mountain in the eastern Highlands of Scotland. These crystals typically exhibit a smoky yellowish-brown hue but can also be greyish-brown.

Smoky quartz crystals can be found in several parts of the world, including Australia, Brazil, India, Kazakhstan, Madagascar, Russia, Zimbabwe, South Africa, Tanzania, Ukraine, Switzerland, and the United States.

Lab-Grown Smoky Quartz Crystals

Some smoky quartz in circulation, particularly from China, is synthetic and grown using hydrothermal methods.

These lab-grown crystals often have unnaturally perfect shapes, sharp terminations, and a colour that's too perfect. One obvious clue is the presence of 'base fuzz', a cluster of small, neatly formed crystals around the base of larger points. I have seen them called something else, relating to anatomy, but I couldn't possibly be any more specific here!

While some lab-grown crystals may look convincing to the untrained eye, experienced collectors and geologists can usually identify them immediately.

Heated Quartz vs Natural Smoky Quartz

When clear quartz or citrine is heated or irradiated, the colour can change to mimic that of smoky quartz.

These treatments can produce a brown or reddish tint, but the results vary, and in some cases, the colour may appear uneven or concentrated in areas that were previously clear.

Distinguishing heat-treated quartz from natural smoky quartz can be difficult, even for experts. Geologists often rely on experience, considering factors such as the crystal’s origin, price, and subtle visual clues like colour tone or surface features.

When people ask questions like 'Is my crystal real or fake?' or 'Is my smoky quartz natural or irradiated?', they’re often hoping for a definitive answer. But geology is complex, and things are rarely so clear-cut.

While visual clues can sometimes help, factors like provenance, geological context, and even information about the seller can be just as important. However, in some cases, lab testing is the only way to be sure.

Article Photos

The smoky quartz with garnet at the top of this article is courtesy of Stan Celestian.

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Dark brown smoky quartz: Courtesy of Ron Wolf. Gypsum (variety selenite): Courtesy of Stan Celestian. Anhydrite: Courtesy of James St. John.