Knowledge

The 6 Different Types of Quartz

“Quartz” refers to compact and crystallized silica forms. For a long time, the various quartz varieties were seen as independent species. They were only intentionally combined after the 19th century after their common chemical nature was discovered by Bergmann, a Swedish chemist, at the close of the 18th century.

For quite some time, silica was believed to be a chemical substance until J.J. Berzelius, also from Sweden, decomposed quartz only to find it consisted of a combination of oxygen and a hitherto unknown element called silicon. Below are the different types of quartz.

1. Rock Crystal

This is colourless, clear quartz which is seen as the authentic quartz image. It’s what most people think of when they hear the term ‘quartz.’ The word ‘crystal’ was coined by the Greeks who at one time believed that quartz was a deeply frozen rock that could not melt again; hence they believed it must have come from the mountains. The only problem with this theory was that rock crystals could be found in places that never experienced ice or snow.

However, the absence of a counter-theory allowed a misguided one to hold. Besides the fact that rock crystal is clear and colourless, most of its other features are common to those found in all macrocrystalline varieties. When exposed to extreme energy radiation, rock crystal can turn into a different type called smoky quartz.

2. Amethyst

This is one of the most popular (a gem) quartz. It features a violet to purple colour and has been used since the ancient times for lapidary works. Most of the amethyst you see today comes from Uruguay and Brazil. The name amethyst alludes to the rock’s alleged ability to shield one from the bad effects of consuming alcohol, “methy,” which is a Greek term that refers to drunkenness. ‘A-methy-stos”, therefore, translates to “someone who does not get drunk.”

The association of this type of quartz with drinking was perhaps informed by the fact that its colour is sometimes similar to that of red wine. Amethyst is a unique type of quartz usually found in various forms and in different rocks. Its colour varies from pale pink-violet to dark blue-violet.

It also features different shades such as red, and in some cases, gray. Its colour is mostly patchy or uneven, only getting more intense at the tips. When exposed to direct sunlight, amethyst pales out rapidly due to ultraviolet radiation.

3. Ametrine

The name ametrine is a combination of ame(thyst) and ci(trine). This quartz crystal spots alternate yellow and violet segments. It has a pinwheel appearance when sliced perpendicular to its c-axis. Ideally, the perfect ametrine should have 3 yellow and 3 violet segments (that’s why it’s alternately known as trystine).

However, this perfect ametrine quartz is extremely rare. While it looks like a beautiful artificial item, it’s actually natural quartz. Although it is a combination of amethyst and citrine, it has more amethyst than citrine. Ametrine is mined in Bolivia the border of Brazil.

4. Aventurine

Although it is a quartz variety, aventurine is not a mineral in the truest sense of the word. It is a quartz rock which contains quartz grains and other minerals such as mica, which is responsible for its metallic sheen.

It is also alternately referred to as aventurine quartzite to distinguish it from aventurine feldspar, which besides being softer and at times more translucent, features a somewhat similar appearance and properties. You know quartz is of the aventurine variety due to its metallic sheen, which could feature alternate colours such as blue, green, yellow, orange, and red.

However, most commercial aventurine is green in colour. Since it is grainy, aventurine features an irregular shape that is so unpolished and raw that its surface resembles that of quartzite or marble. Unlike marble, however, it is non-porous but as dense and compact as quartzite. You can find high-quality aventurine in India, Norway, and Brazil.

5. Blue Quartz

This is blue macrocrystalline quartz. It includes three types of quartz: quartz crystals, crystalline quartz, and the macrocrystalline quartz. It is safe to say that the name “blue quartz” refers to any rock crystal that looks blue, not a specific type of rock. However, all three forms of blue quartz owe their colour to the compound presence of other minerals and not lattice defects or some other built-in trace elements as is the case with, for instance, amethyst.

Despite the ‘blue’ inference, the colour of blue quartz varies from gray to deep blue. Since it gets its colour from a combination of other minerals and not by trace elements, natural blue quartz is translucent, never transparent. You can find grains of natural blue quartz embedded in igneous rocks.

6. Citrine

This is a yellow, transparent and extremely rare macrocrystalline quartz. It is so rare that most of what sells in the market as citrine is actually amethyst that has been heat-treated. There is some confusion as to what constitutes natural citrine.

Some people contend there are two types of citrine, while others add heat treated amethyst as the third type. Whatever your contention, what qualifies quartz as citrine is the colourizing agent, which should be fine and evenly spread in the crystals. The appearance of the crystals should be transparent and more or less evenly and finely distributed in the crystals. The crystals should also appear transparent. If a crystal is opaque or has a fibrous or grainy yellow appearance, it is not a citrine.

Ronald Ryan

I'm a self-proclaimed science geek and all-around nerd. Useless fun trivia seems to be my forte. If you ever need to hear a good dad joke, I'm your guy!

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