See the Smoky Quartz gemstone page for more details. Rose Quartz The rosy pink variety of Quartz is known as Rose Quartz, and its color is usually soft, ranging from very light pink to medium pink in intensity.
Rose Quartz is often milky or hazy, and it may lack good transparency. See the Rose Quartz gemstone page for more details. Rock Crystal The colorless, transparent variety of Quartz, free of any impurities , is known as "Rock Crystal". Flawless and very large cuts may be cut from Rock Crystal. Milky Quartz Milky Quartz is the white, translucent to opaque variety of Quartz. Though very common in nature, it is not used as a gemstone.
Rutilated Quartz Colorless Quartz with golden yellow Rutile inclusion s, as hairlike growths within the gemstone, are known as Rutilated Quartz. See the Rutilated Quartz gemstone page for more details. Ametrine Ametrine is an interesting, color-zoned combination of purple Amethyst and brownish-yellow Citrine. See the Ametrine gemstone page for more details. May also be called "Green Amethyst" by some jewelers. Blue Quartz The blue variety of Quartz, which is uncommon in nature, is seldom used as a gemstone.
Most "Blue Quartz" is clear Rock Crystal irradiated with gold to from a deep sky blue color. Blue Quartz may also refer to a dull grayish-blue Quartz in massive form with Crocidolite inclusion s. Tourmalinated Quartz Colorless Quartz with Tourmaline inclusion s, often as thin long black crystals, is known as "Tourmalinated Quartz". It is not common, and the chatoyant effect is usually weak.
Cat's Eye Quartz is usually grayish in color and translucent. All forms of Quartz are used as gemstones, and they are all affordable. They are cut into various gemstone cuts and cabochon s, and used in all forms of jewelry. Lesser quality stones are often tumbled for use in bracelets, necklaces, and as costume jewelery.
Large spheres and carvings are also cut from all the Quartz forms. Due to its abundance and lack of luster, Rock Crystal is not commonly cut into gemstones, although some very large spheres and sculptures are carved from it. Small crystals of Rock Crystal are sometime worn as pendant s, sometimes being polished and smoothed, and sometimes in their entirely natural crystal form.
As such it is an excellent abrasive material. Quartz sands and finely ground silica sand are used for sand blasting, scouring cleansers, grinding media, and grit for sanding and sawing. Chert: Chert is a microcrystalline or cryptocrystalline quartz. This specimen is about four inches ten centimeters across and is from Joplin, Missouri. Quartz is very resistant to both chemicals and heat.
It is therefore often used as a foundry sand. With a melting temperature higher than most metals, it can be used for the molds and cores of common foundry work. Refractory bricks are often made of quartz sand because of its high heat resistance.
Quartz sand is also used as a flux in the smelting of metals. High-Purity Quartz Sand: Did you know that quartz is the main ingredient in glass? Geologists locate deposits of sand or sandstone that are composed almost entirely of quartz. This material is mined, processed to remove impurities, and then melted at the glass factory. The sand above was mined from the St. Peter Sandstone of Wisconsin. Quartz sand has a high resistance to being crushed.
In the petroleum industry, sand slurries are forced down oil and gas wells under very high pressures in a process known as hydraulic fracturing.
This high pressure fractures the reservoir rocks, and the sandy slurry injects into the fractures. The durable sand grains hold the fractures open after the pressure is released.
These open fractures facilitate the flow of natural gas into the well bore. Silicified wood: Silicified "petrified" wood is formed when buried plant debris is infiltrated with mineral-bearing waters which precipitate quartz. This quartz infills the cavities within the wood and often replaces the woody tissues. This specimen is about four inches ten centimeters across and is from Yuma County, Arizona. The best way to learn about minerals is to study with a collection of small specimens that you can handle, examine, and observe their properties.
Inexpensive mineral collections are available in the Geology. Quartz sand is used as a filler in the manufacture of rubber, paint, and putty. Screened and washed, carefully sized quartz grains are used as filter media and roofing granules. Quartz sands are used for traction in the railroad and mining industries. These sands are also used in recreation on golf courses, volleyball courts, baseball fields, children's sand boxes and beaches.
Quartz crystal: A Herkimer "Diamond" quartz crystal in dolostone. This specimen is about six inches fifteen centimeters across and is from Middleville, New York. One of the most amazing properties of quartz is the ability of its crystals to vibrate at a precise frequencies. These frequencies are so precise that quartz crystals can be used to make extremely accurate time-keeping instruments and equipment that can transmit radio and television signals with precise and stable frequencies.
There are two main kinds of crystal quartz, Macrocrystalline and Cryptocrystalline. Macrocrystalline, or simply Crystalline, has crystals with distinct shapes recognizable to the naked eye, that run the gamut from tiny druzies all the way up to crystals larger than a man.
The photo above shows a piece of druzy with eye visible crystals. This makes it a crytaline quartz. Dumortierite quartzisusually listed with the crystalline group although some sources list the latter three with the microcrystalline group. We will include them in the crystalline group. Colored crystalline quartz varieties generally form as various water solutions are deposited in pegmatite dikes and veins over long periods of time, resulting in slow crystal growth that can yield massive specimens with perfect clarity, that facet beautifully.
Appearances and colors of quartz vary greatly, but their basic gemological properties remain consistent throughout the entire family, with few exceptions:. Crystal System: Trigonal hexagonal prisms in many forms like crystalline masses, cryptocrystalline, granular, and in veins. Mohs: 7 What does this mean? Refractive Index: 1. Cleavage: None to indistinct; conchoidal fracture to uneven; brittle, and tough in cryptocrystalline varieties.
A few types of quartz that are not colorless and natural are: Latte Quartz, Champagne Quartz. Colorless quartz is always untreated. Colored stones can occasionally be enhanced in color by dying a combination of bathing in color agent solutions, fallowed by heating , irradiation bombardment with low level radioactivity , or heating. Reliable gem dealers will always inform their customers about any kind of treatment. Some quartz gems can lose their color saturation over a period of time in daylight.
The original color can be restored by X-ray radiation. Normally untreated, but Amethyst may have a treatment of heat of degrees F degrees C which results in light yellow, red-brown, green or colorless varieties. Some amethysts can lose their color saturation in daylight. Prasiolite is green amethyst which will be listed separately as Prasiolite.
Aventurine is a type of Quartz frequently used for carvings and cabochons. Aventurine is mainly dark green sometimes with a glittery metallic appearance caused by included green mica. Aventurine is not known to be enhanced. Quartz crystals of different colors often form together to form interesting bi-colored stones. These can be part natural Citrine and smokey quartz, or amethyst and colorless quartz, these gemstones are very attractive. When natural bi-colored quartz is found in nature there is no need for enhancements or Treatments.
Reputable vendors will disclose any treatments applied to the gems they sell. Crystalline quartz is in the Chalcedony family a gorgeous rainbow blue color, A milky white with rainbow effect much like moon stone, This quartz is Heat Treated.
Many carnelians being offered in the market today are actually Agates which have been dyed and then heat treated. There is a way to identify natural carnelian. The dyed agate will display striping when held against the light, while the natural carnelian will show a cloudy distribution of color.
Natural carnelian is increasingly rare. Carnelian can be Heated to darken color. Chalcedony, chalcedony will mean any translucent, crypto crystalline quartz with a single color, whether it has a special variety name or not. Its colors are bluish, white, or gray. The various types differ in color due to metallic impurities, such as iron, nickel, copper, and titanium, present during crystallization.
It is distinguished by having multiple colors. Banded agates are some of the most popular. A rarity is the so-called fire agate. The iridescent colors of red, gold, green and rarely, blue-violet, result from interference between light rays traveling through these thin layers. Agate jasper, which grows together with agate, is yellow, brown, or green blended. Onyx is a layered stone with a black base and a white upper layer.
Agate is normally dyed with bright colors. It is an opaque, dark-green chalcedony with red spots caused by iron oxide. Bloodstone is not treated in any way. The most unusual and most valuable type is from Oregon. The Aqua blue chalcedony is dyed. In the narrow sense, comes in bluish white or gray. Uni-colored chalcedony sometimes is called ONYX.
Black and colored onyx is dyed. Carnelian ranges in color from yellow-orange to rich, near reddish orange, to orangey brown, and varies from semi-opaque to highly translucent.
Despite being less popular than amethyst, citrine is actually much rarer. In fact, many sellers heat amethyst at high temperatures until it turns yellow, and they sell it as citrine.
It can be hard to tell apart citrine from heated amethyst; the best way to differentiate though it is not often readily available is to look at the crystals in polarized light: citrine is dichroic in polarized light it absorbs different polarizations in different ways while amethyst is not. It can be obtained either naturally or artificially. It also has two varieties: Morion and Cairngorm. Smoky quartz is typically found in pockets around igneous rocks.
However, not all dark quartz is smoky quartz. Like citrine, smoky quartz exhibits dichroism in polarized light. Rose quartz varies in color from light pink to rose red, usually due to titanium or iron although manganese can also be present. Rose quartz can be hazy, translucent, or anything in between. This is due to microscopic fibrous inclusions of a pink borosilicate mineral.
Its pink hue is believed to be caused by aluminum and phosphorous atoms that replace the silicon in the crystalline lattice. Prasiolite, also called vermarine , is a green variety of quartz.
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