Quartz is one of the most common, unusual, unique and fascinating crystals found on the surface of the earth. There are literally tens of thousands of locations where quartz is mined. It comes in all shapes and sizes, colors and habits. Quartz is also the foundation which other crystals use to grow in, around or on top of. For a beginner, it is easy to get lost in the myriad of quartz crystals that grow within the earth. This article helps to break down colorful quartz.
Let’s start with the basic clear Quartz, which is also called “Rock Quartz or Rock Crystal”
The chemical formula is SiO2, which is “science speak” for Silicon dioxide, also known as Silica. It has been known since ancient times. Silicon Dioxide is known for its hardness, scoring a 7 on the Moh’s Hardness Scale.
Quartz comes in a variety of colors including Purple, Rose, Red, Black, Yellow, Brown, Green, Blue, and Orange. The color is due to mineral impurities that are present when the crystal is in it formative stages.
Clear Quartz is also called Rock Crystal and is a transparent colorless variety of quartz. White or Milky Quartz is a semi-transparent to opaque white-colored variety of quartz.
Colorful Quartz
Amethyst is quartz that is colored by iron impurities. The range of color includes reddish-violet tints to pale or almost colorless shades, and deep, rich tones of pure violet.
Rose Quartz is colored by impurities including titanium, iron or manganese. Not everyone is in agreement as to what truly colors Rose Quartz and there are still tests being run. A mineral similar to Dumortierite is a possibility.
Smoky Quartz occurs in nature when rock crystal quartz is exposed to natural radiation from radioactive elements or adjacent radioactive rocks over long periods of time.
Morion describes a unique Smoky Quartz that is very nearly black.
Red Quartz is colored by Hematite which is a type of Iron Oxide. You may have seen the Red Capped Amethyst from Canada or the Red Quartz from Arizona.
Blue Quartz is often colored by inclusions of fibrous magnesioriebeckite or Crocidolite. Others are
colored by Dumortierite.
Tangerine Quartz is also colored by Hematite /iron oxide, but in this case, it is a dusting on the OUTSIDE of the crystal, not within the crystal structure.
Citrine is colored by trace amounts of iron impurities within the crystal structure of quartz. (Natural,
not heat treated. Heat treated Citrine is actually Amethyst).
The term “Prase” is simply a name to describe the leek green color any type of quartz. Prasiolite is a leek green crystal (rare) found in nature. It is more often produced artificially from violet amethyst or yellowish quartz by a combination of heat treatment and cobalt-60 or E-beam Gamma irradiation.
Amegreen Quartz is often described as a rare combination of Amethyst, Prasiolite and Quartz. Since Prasiolite is naturally a rare find, it is more likely that Amegreen is heat treated. Although Prasiolite is typically accompanied by amethyst, the jury is still out on this one.
Aventurine
Aventurine is a type of quartz characterized by its translucency and the presence of platy mineral inclusions that give a shimmering or glistening effect termed aventurescence.
Blue Aventurine is colored by inclusions of the mineral Dumortierite.
Green Aventurine is colored by Chrome-bearing fuchsite (a variety of Muscovite mica).
Yellow to Orange to peach “Aventurine” is colored by hematite or goethite and is more accurately defined as Quartz, as it has no platy mineral inclusions (like Mica or Pyrite), which is necessary to be called Aventurine. However, I have seen it called both Quartz and Aventurine.
Red/Pink Aventurine is colored by inclusions of Hematite/iron oxide inclusions.
White Aventurine is not as common but really brings out the sparkle of the mica inclusions.
References:
http://www.quartzpage.de/prasiolite.html
http://www.mineralminers.com
http://www.healing-crystals-for-you.com/aventurine-stones.html
www.mindat.org
www.gemdat.org