Quartz is the most abundant single mineral on earth. It makes up about 12% of the earth's crust. It's no wonder that Quartz has gained the reputation of being the "chameleon" of gemstones. Pure Quartz often called "rock crystal" was used in ancient times to make crystal balls and bowls.

In today's market we also see many of the quartz varieties set in gold jewelry. Varieties such as amethyst, citrine, rose quartz, onyx, agates, chrysoprase and numerous others. 

Quartz varieties are commonly separated into two groups based on the size of the individual grains or crystals. Macrocrystalline quartz has individual crystals that are distinguishable with the naked eye. Cryptocrystalline quartz consists of individual crystals too small to be easily distinguishable under the microscope.

Some of the Macrocrystalline quartz varieties are: Amethyst, Ametrine, Cat's-eye Quartz, Citrine, Rock Crystal, Rose Quartz, Rutilated Quartz and Smoky Quartz.

The Cryptocrystalline varieties of quartz may be separated into two types. fibrous and microgranular. Chalcedony is the general term applied to the fibrous Cryptocrystalline varieties. Agate is an example of a fibrous cryptocystalline quartz. Carnelian, Chrysoprase
and bloodstone are other chalcedony varieties.

Chert is the general term applied to the granular Cryptocrystalline varieties of Quartz. Flint and Jasper are examples. There are also Quartzites like Aventurine, that are rock not mineral.  Quartzites are basically interlocking macrocrystalline quartz grains combine with other color giving minerals.

The varieties of chalcedony are divided more by character than by color. Chalcedonies are gemstones such as agate, jasper, common opal, onyx, Chert and etc. 

Many chalcedonies have grown in popularity with the growing appreciation for carved gemstone. spheres, eggs and ect. Unusual quartz types like drusy quartz, with it's tiny sparking crystals and rutilated quartz, which has shining gold needles inside. Are adding variety to one-of-a-kind jewelry projects.

Some of the more common of these types are Chrysoprase (a pure green agate), Sard (a yellow to brown agate), Sardonyx (banded sard), Onyx (black and white agate), Carnelian (a yellow to orange agate), Flint (a colorful and microscopically fibrous jasper), Jasper (a colorful opaque agate) and bloodstone (a green with red speckled jasper) just to mention a few.

Quartz Uses  - Quartz is found in many everyday items, including sandpaper and other abrasives, soap and ceramics. It is also in high-tech items such as radios, TVs, Clocks, watches and computers. It was found to be highly useful in modern technology, because in electric tests, it was shown to produce regular electric pulses and field changes that inventors could predict.

The weathering of igneous rocks removes most other minerals. But Quartz grains resist the erosion process. They collect together and when compressed make Sedimentary formations. When Sedimentary rocks containing Quartz enter a Metamorphic process, the size of the Quartz grains change greatly.

Quartz has a Trigonal crystal structure, containing four axes, three of which intersect to form a plane,  intersected by the fourth. Impurities or disruptions during the formation process can form crystals that contain encrustation's and or phantom crystals. Crystals can also form hexagonal prisms, twinning, or double termination's. They can show up in Geodes in any or all of the Quartz forms.

Phantom quartz shapes are sometimes present in the interior of quartz crystals, outlining an earlier stage of the crystal's formation. These phantoms are usually composed of other minerals such as chlorite or other varieties of quartz . This leaves a coating on most or all of the surfaces of the crystal during its growth. The crystal then resumes its crystallization creating a phantom crystal outline within itself.

One other mineral shares isostructural crystal formation with Quartz. It is a very rare Phosphate called Berlinite (A1PO4). Herkimer Diamonds are Quartz crystals with double termination's and Tourmalinated Quartz contains hairs of Tourmaline crystals.

Rutilations in Rose Quartz can create a star effect. Rutilated Quartz is a variety of Quartz Crystal containing impurities of Titanium Dioxide, that form needles within the Quartz. Some have called it Venus? Hair Stone.

Smoky Quartz has colors that range from tan to light gray which makes it rare in the mineral world .There are only a few others, that display brown or black coloring. It is sometimes misleadingly sold as Smoky Topaz.