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GEMSTONE QUARTZ

What do the following have in common?

Agates (all forms); Amethyst; Amethyst Quartz; Ametrine; Aventurine; Black Onyx; Bloodstone; Blue Quartz; Cairngorm; Carnelian; Chalcedony; Chert; Chrysoprase; Citrine; Crystal; Dendritic Agate; Fire Agate; Flint; Fulgurites; Geode (most forms); Hawk’s Eye; Heliotrope; Herkimer Diamond; Jaspers (all forms); Lodalite; Madeira Citrine; Moss Agate; Moukaite; Mtorolite; Onyx (most forms); Opal (all forms); Opalite; Petrified Wood; Plasma; Prase; Prasiolite; Precious Opal; Quartz Cat’s Eye; Quartzite; Rock Crystal; Rose Quartz; Rutilated Quartz; Sandstone; Sard; Smokey Quartz; Star Quartz; Thunder Egg; Tiger’s Eye; Tourmalineated Quartz; Glass; and much more.

They are all forms of QUARTZ!

Quartz (SiO2 – Silicon dioxide) is one of the most common minerals in the earths’ crust, and is probably the most prolific among the gemstones. Each of these gemstones is a type of quartz, in one, or more, of its various crystalline forms. Variations within a form are caused by impurities within the molecules and inclusions within the gemstone.

There are three basic forms of Quartz gems;

Macrocrystalline, Cryptocrystalline, and Amorphous Silica.

This series will try to explore and describe many of the various forms of Quartz gems.
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Macrocrystalline Quartz
(Crystals that can be seen with the naked eye.)

Crystalline quartz - (generally) common properties: Luster: Vitreous.
Moh’s hardness: 7. Density: S.G. 2.65. Transparency: Transparent to translucent.
Cleavage: None. Fracture: Conchoidal, brittle. Crystal system: (Trigonal), hexagonal prism.

Rock Crystal: Clear as water. In fact, “crystal”, from krystallos, pertains to the earthly Ice Palace of the Greek gods that couldn’t even be melted by the sun. The hexagonal Quartz crystals can grow from a microscopic size to behemoths, weighing many tons. Usually, single-terminated, well-formed crystals grow in cavities in the same, or other host rocks, and they are attached at one end to that host rock. Under other circumstances, the crystals can grow by them selves and have beautiful terminations on both ends. Many of these double-terminated crystals have been mistaken for Diamonds, and at a source near Herkimer, N.Y. the crystals are known as “Herkimer Diamonds”. It is not uncommon for other mineral crystals to include (grow within) the Quartz crystal, and many of these included varieties are considered to be gemstones, too. These will be discussed in a future section of this series.

Virtually, no other gemstone has piqued the imagination as much as Quartz, when it comes to metaphysical and healing properties. The Quartz crystal has been an object of reverence in most nature-based beliefs. Shamans and healers use, and have used Quartz crystals in their rites and practices. It is said that you can see the future in a (Quartz) Crystal Ball. Since Mesolithic times (12th to 8th millennium B.C.), Quartz crystals have been worn, in many forms, - for their beauty and as talismans. They were worn as crystals, water worn pebbles, and/or formed into various shapes. To wear them, they were knotted on cords or strung through primitively bored holes. Even today, there are millions of people who believe in the powers of the Quartz crystal.

In modern times, it was found that Quartz crystals actually do have special physical properties. One is, by applying an electrical current to a piece of Quartz crystal, it will vibrate at a standard rate. This is used to maintain perfect timing in your electronic timepieces and other electronic devices. The second property is piezo-electricity, or the property of producing an electric spark when it is hit.

Today, great quantities of perfect synthetic Quartz is produced for the electronics industry, and for piezo-electricity uses, such as, producing the spark that ignites the flame in your “pilot-less” gas stove. Also, it was found that by adding color and impurities to this synthetic Quartz, new forms of “synthetic Quartz gems” could be produced, such as, “Strawberry Quartz”, “Pineapple Quartz”, etc.

Although Quartz crystal can be found all over the world, and on the moon, too, it is commercially mined in: Brazil; Madagascar; Canada; Arkansas, California, Colorado & New Jersey (USA); and The Alps..

More Valuable Crystalline Variations:

Milky Quartz: A white, translucent to opaque form of Quartz crystal. The white color is caused by microscopic fluid inclusions. When massive it can contain small particles or crystals of gold. When used in jewelry it is known as Gold Quartz. Milky Quartz can also contain, or be stained by other metals, native or ore.

Commercial sites include: the Brazil; Madagascar; Russia; Namibia; Germany; Greece; England; USA – New York, New Hampshire, Rhode Island, Alaska, and California.

Amethyst: The is most highly prized Quartz crystal gem. This lilac to rich purple form of Quartz is colored by the element iron. Many times, as Amethyst crystals grow, the color can form in zones, with the deepest color in the tip. Amethyst crystals and cut stones can show these zones as color bands. Some zoned crystals show “ghost crystals”, like the growth rings in a tree. Amethyst can be found in giant crystal filled geodes in Brazil. The color in Amethyst can be unstable. It can be changed by heat, and diminished with long exposures to sunlight.

The name Amethyst comes from the ancient Greek word, “amethystos”, which means “not drunk”. According to Greek mythology, when you wear Amethyst you can not become drunk while drinking wine. Historically, Amethyst was treasured by ancient civilizations, such as Egyptians, Hebrews, Etruscans, Greeks, Romans, Chinese, etc. Small Amethyst cameos were found in ancient archaeological sites in China. Amethyst represented one of the twelve tribes, and was an important component in the breastplate of the ancient Hebrew priests. In past years, Amethyst was a favorite gem worn by high officials of the Catholic Church.

Important sources include: Brazil; Uraguay; Africa; Siberia; USA; Canada; Mexico; Japan; China; Australia; Russia; etc.

Amethyst Quartz: A.K.A. Chevron Amethyst. A translucent to opaque crystal gem made up of layers of Amethyst and Milky Quartz or clear Quartz crystal.

Praisiolite: AKA Green Amethyst. An unnatural form of leek-green Quartz created by heating a violet Amethyst or yellow Quartz, both from the Montezuma mine in Brazil. Lately, it has been found that Amethyst from a mine in Arizona (USA) also converts to Praisiolite when heated. It is common for the color in Praisiolite to fade in sunlight.

Citrine: Natural Citrine is quite rare, and when found in nature, it is a pale yellow to lemon color, only. When heated, natural Citrine can change to a dark yellow to light brown color. Like Amethyst, Citrine is, also, colored by Iron. The purple color in some Amethyst is unstable, and when it is heated to 878 degrees F. it becomes yellow-brown, and when heated to 1030 degrees F. it becomes dark yellow to red-brown. A red tint is common in heat treated Citrines. It is known that as far back as the Middle Ages, Citrine has been produced by the heating of Amethyst. Citrine should be protected from excessive exposure to light and heat.

Fancy, false names such as Madeira, Bahia, or Rio Grande Topaz give the impression they are more expensive gems and are no longer accepted in the trade, although Madeira Citrine is acceptable when the gem comes from that location.

Sources of natural Citrine are: Brazil; Madagascar; Myanmar; USA; Argentina; Africa, Russia; Scotland; and Spain.

Ametrine: A natural, delineated, combination of Amethyst and Citrine, within the same crystal. The first Ametrine crystals were found in Bolivia in the late 20th century

The original source of Ametrine is Bolivia, but it has also been found in Brazil.

Crystalline Quartz gems & Quartz gems:

Smokey Quartz: These smoky yellow to brown to black transparent crystals are colored by the interaction of Aluminum and Lithium ions in the crystal matrix interacting with ambient radioactive radiation from Uranium and Thorium in the surrounding rocks. (This gem does not give off dangerous radiation.) It’s not uncommon to see “phantom crystals” within a crystal. These phantoms are caused by variations in color as the crystal grew. In Scotland, Smoky Quartz is known as Cairngorm, where it is the national stone. Smoky Quartz is also, incorrectly known as Smoky Topaz so as to raise it’s price.

When heated, Smoky Quartz changes to tones of yellow. This color change can be reversed by the application of X-rays. It is not uncommon to find Rutile crystal (needles) inclusions in Smoky Quartz.

Smoky Quartz is found in: Brazil; Madagascar; Scotland; USA; Switzerland; Russia; Australia; Canada; France; Germany; etc.

Morion: An almost black form of Smoky Quartz.

Lemon Quartz: When heated, some Smoky Quartz turns to a lemony color. Variations can run between a deep lemon color and a smoky lemon.

Rose Quartz: This pink transparent crystal to a turbid pink massive translucent gemstone has been used for adornment since ancient times. Titanium and manganese are responsible for this gem’s color. Minute Rutile needle inclusions can form “Cat’s Eyes” and six-rayed “Stars” when the gem is cabochan cut. Star Rose Quartz is unique in the fact that the star is seen by transmitted light, instead of the usual reflected light. Rose Quartz can fade to gray because of its’ sensitive to excessive exposure to heat, air, and light

Rose Quartz is found in: Brazil; Germany; Madagascar; India; Africa; Sri Lanka; USA; etc.

                                                      -- Included Quartz crystal --

Quartz crystals can be included by numerous other minerals (usually crystals), water, and even gasses. A few of the minerals that are included in gem Quartz crystals are: Rutile; Tourmaline; Chlorite; Goethite; Manganese dendrites; Pyrolusite; Huebnerite; Garnet; Pyrite; Hematite; Gold; etc.

Star & Cat’s Eye Quartz: See Rose Quartz and Smoky Quartz.
Cat’s Eyes are seen when coarse Quartz that is included with fibrous parallel hornblende-asbestos is cabochon cut. Deposits are found in Sri Lanka; Brazil; and India.

Cat’s Eye and Star Rose Quartz is found in: Brazil; Sri Lanka; Kenya; Mozambique; Namibia; New York; Georgia

Rutilated Quartz: AKA Sagenite and “Hair stone”. Usually Rock Crystal, but can be Smoky and Rose Quartz, that is included with fine golden to reddish-brown to black needles (crystals) of Rutile. Rutile needle displays can be random, but beautiful “sprays” of colorful Rutile crystals are highly prized. Included Rutile can produce a chatoyant effect when the needles are fine and in parallel alignment.

Rutilated Quartz is found in: Brazil; the Alps; Australia; Madagascar; South Africa; Sri Lanka; USA; Russia; etc.

Tourmalineated Quartz: Same as Rutilated Quartz, except the needle-like inclusions are usually green to black Tourmaline. In some cases, the Quartz crystal can take on a green color from green Tourmaline

Usually found in pegmatites in Tourmaline mines in Brazil, and all around the world.

Lodalite: AKA Picture Quartz. Clear Quartz crystals that are included with chlorite and other dark mineral crystals that form visual landscapes, or Iron and Manganese that forms tree or moss like dendrite inclusions. Beautiful phantom patterns are created when inclusions of fine Chlorite orient along the growth faces of the Quartz crystal. Values increase with the beauty and imagery in the stone.

Sources include Brazil; Madagascar; Russia; etc.

Aventurine: A sparkly form of included Quartz. Usually green with a flashy, metallic iridescence caused by tiny crystals of fuchsite (a green Chromium Mica) included in Quartz. Also, found in reds to peach to golden brown caused by tiny, included leaves of Hematite or Goethite, and silvery brass caused by tiny included mica crystals. Blues, and other colors are probably dyed.

Aventurine was well known in ancient China, where it was called “Yu,” or “Emperor stone”.

Found in Russia; Austria; India; Brazil; Spain; Chile; Tanzania; Russia; Austria

Prase: A.K.A. Emerald Quartz. A rare, leek-green aggregate Quartz whose color is the result of included hair-like crystals of Actinolite.

Deposits exist in Austria, Finland, Germany, and Scotland.

Blue Quartz: Inclusions of Crocidolite fibers produce a turbid-blue color in a coarse grained Quartz aggregate.

Deposits are found in Austria, Brazil, Scandinavia, South Africa; & the U.S.A.

Hawk’s Eye: A blue to blue-green Quartz gem with chatoyancy, or a silky sheen “eye”, that seems to float across its' surface. This type of gem is called a pseudomorph, or a mineral that has replaced another. In this case, Quartz has replaced fibrous, Crocidolite (with iron), but the Quartz has still retained the original fibrous structure. As light plays across the surface of the tightly aligned fibers, bright lines (eyes) that are perpendicular to the fibers, seem to move across the gems’ surface. Commonly, this gem is found in thin layers in iron rich, Jasper deposits. When the iron and Jasper are included in the gemstone, they become a matrix, and the resulting gemstone is called, Tiger Iron or Tiger Iron Matrix.

Important deposits are in: South Africa (export is forbidden); Australia, Myanmar; India; Namibia; and California (USA).

Tiger’s Eye: A golden-brown variety of Hawk’s Eye, that got its’ golden color by the oxidation of the iron in the Hawk’s Eye. When the Tiger’s Eye is heated, the iron oxide changes to a different form and red Ox-Eye is formed. An acid bath can bleach Tiger’s Eye to a gray color. The gray Tiger’s Eye is falsely sold as Cat’s Eye, or it can be dyed to any other color.

Tiger Iron matrix: Thin, wavy layers of Tiger’s Eye, intertwined in its’ iron-Jasper matrix.

Onyx: There are two varieties of onyx. The first one is defined as a layered chalcedony with straight, even, parallel banding, with two, or more, contrasting colors, preferably, black and white. This form of onyx is very important in the cameo industry. The second one is described as any single colored chalcedony, such as Black Onyx. Today, and historically, too, black and other colors are usually produced, artificially.

Sard: A dark red-brown to brown form of chalcedony. The color is less intense, and browner than carnelian. The original sources on the island of Sardinia were depleted eons ago. Today, dark carnelian is sometimes called Sard. Many of the “sards” on the market, today, are really artificially colored chalcedony.

Sard figures in Biblical scripture. It was one of the twelve gemstones that, by commandment, were included in the breastplate of the Hebrew high priests. Plus, it appears in the book of Revelations in the Christian Bible.

Sard is found in Sri Lanka, California (U.S.), India, and China.

Sard onyx: Bands of Sard and white onyx. Sard onyx is used for cameos, and when dome-cut it produces a “protective eye”. At one time, Sard onyx was considered to be more valuable than Gold, Silver, and Sapphires. Today, and historically, too, the colors might be produced, artificially.

Bloodstone / Heliotrope: An opaque, dark-green chalcedony with red spots. Tiny inclusions of chlorite and hornblende produce the green color, and iron oxide (rust) produced the red spots. The colors can vary, with small amounts of other colors present. In some circles, the green background, or by itself, is called “plasma”.

Bloodstone has been significantly featured in the Judeo-Christian religions. In Judaism, it was one of the twelve gemstones that, by commandment, were included in the breastplate of the Hebrew high priests. In Christianity, the red spots were supposed to be the frozen drops of blood shed by Jesus while he was on the cross.

There are significant deposits of bloodstone in India, Brazil, Australia, China, and the United States.

Moss Agate: A massive, clear chalcedony with intertwined green, brown, or red moss like or tree like inclusions. The mossy inclusions can be metallic salts, or the oxides of iron or manganese.

Dendritic Agate: Clear chalcedony, where the individual, dark dendrites can be seen. The dendrites are primarily composed of oxides of manganese or iron. When the dendrites form beautiful images or scenes, the value of this gem rises.

One well-known variety of dendritic agate is the highly prized Montana Agate, from the streams of Montana (U.S.). This gemstone is known for its’ exquisite ferns and scenes.

Scenic agate is a form of dendritic agate in which the included dendrites form a landscape-like image. The scenes are usually in tones of brown and red. Fine scenic agates can be very valuable and are highly prized by jewelers and collectors.

Enhydritic Agate: AKA Enhydro or Water stone. It is a nodule of agate or chalcedony that is partially filled with water. Usually, the water can be seen through the wall of the nodule. They are collectors’ items.

Agate: Agate is considered to be a form of chalcedony with concentric bands, or fortifications, “eyes”, “plumes”, and other variegated patterns. With the concentric agates, each band is made up of fine cryptocrystaline fibers of quartz that are aligned perpendicular to the edge of the individual band layers. The bands can be all the same color, or in various colors depending on chemical contaminates in the original precipitate. Agate varieties include: eye; layer; fortification; orbicular; plume; tubular; dendritic; brecciated; moss; fire; scenic; enhydritic; etc.

Agates generally get their name by what it looks like, where it was found, who found it, the name of the girlfriend (or mule) of the discoverer, etc. There must be hundreds of different agate names.

A few popular Agate varieties include:
Blue lace agate – a light to dark banded agate.
Crazy Lace Agate – a warm toned lacy, banded agate from Mexico.
Turritella agate – a brown colored agate filled with turritella shell fossils.
Botswana agate – a gray to pink fortification agate from Botswana.

Major agate deposits are found in Brazil, Uruguay, Australia, China, Madagascar, Mongolia, Botswana, Namibia, Wyoming, and Montana. Minor deposits (commercial and other) are found in virtually every part of the world.

Fire Agate: A rare, dark brown based agate with exciting flashes of colorful “fire” emanating from its’ depths. This “fire” is created by layers of minute inclusions of goethite or limonite within the chalcedony. Red fire is the most valued color. Next in popularity is the blue and green fire mix. The least popular fire color is brown.

Fire agate is a relatively new gem on the market. This agate is almost always found as botryoidal or mammillary crusts on host rocks. The two major deposits are in Sonora, Mexico and Maricopa Co. in Arizona, (U.S.) Mexico and SW US

Geode: A hollow agate nodule, usually with quartz, or other crystals protruding into the center.

Thunder egg: A solid agate nodule. Sometimes filled with both concentric and parallel-banded agate.

Jasper: Formerly known as Hornstone, this grainy, opaque gemstone is 80% chalcedony, plus 20% +/- opal, quartz, and foreign minerals. Some scholars consider jasper to be a colorful variety of chert. The colors and patterns are controlled by the type and quantity of foreign minerals that are interspersed between the jaspers’ microscopically fine grains.

Jasper is found in virtually every corner of the earth. Although its’ primary colors are yellows, browns, reds, greens, plus black and white, Jasper can be almost any color or pattern you can imagine. It can be a solid color; scenic, spotted, banded, pictorial, orbicular, floral, or even have strange variegated patterns. Like agate, Jaspers are generally named according to what it looks like, where it was found, who found it, the name of the girlfriend (or mule) of the discoverer, etc. There are virtually thousands of different jasper names in English, and there are probably thousands more in every other language, spoken, and dead.

I have found that there are a number of gem beads on the market that are called “Jasper”, even though they aren’t. It’s an easy, catchall term for any unnamed stone.

A few popular Jasper varieties include:
Brecciated or Poppy Jasper – a deep red and warm toned jasper that was shattered and then naturally cemented back together with jasper or chalcedony.
Leopard Skin Jasper – a dark, brown to red spotted jasper, from Mexico, is reminiscent of a leopard pelt.
Moukite – a beautiful variegated, reds to golds to white jasper from Australia.
Ocean Jasper – an orbicular jasper from the coast of Madagascar, and it can only
be mined at low tide. The jasper on the dry side of the hill has a different name.
Picasso Jasper – this stone from Utah has the muted blacks, grays, tans, and a touch of red that is reminiscent of modern, abstract paintings. This stone might actually be a form of marble.
Picture or scenic Jasper – a warm toned, layered, jasper that looks like a scenic
Painting of vistas in the southwest U.S. It is found in Africa, Idaho (U.S.), etc.
Porcelain Jasper – a beautiful jasper that looks like a mosaic made up of broken pieces of pink to purple porcelain.
Red Jasper - a beautiful brick red jasper from India. The coloring agent is iron.
Also, found in Australia.
White Jasper - a solid snow white jasper.
Wild Horse Jasper – a scenic jasper from Wild Horse Canyon, Oregon (U.S.)
Zebra Jasper – a black and white striped jasper. (It may not be real jasper)

Petrified Wood: A fossil, where the wood is replaced, cell for cell, by one, or more of the following: chalcedony, jasper, and opal. Dull grays and browns are the usual colors, but it can also have yellows, pinks, reds, light brown, black, and sometimes blue to violet. Like the wood it has replaced, petrified wood shows all of the characteristics of the original piece of wood, including rings, branches, and insect holes

Petrified wood is usually found in “forests” of petrified logs and branches. One of the most famous discoveries is The Petrified Forrest National Park, near Holbrook, Arizona (USA). Commercial sources include Egypt, Argentina, Canada, and U.S.A. (Wyoming and Nevada). Smaller sites occur all over the world, including Antarctica.

Flint: A purer, stronger form of chert. It has a waxy to dull luster, and its’ colors range from whitish to dull gray to smoky-brown to black. Used by stone-age peoples to create projectile points, knives, and other tools, plus ornamentation. By striking a piece of flint with a piece of iron or steel, one can create a spark and start a fire.

Chert: This gray stone is almost identical to its’ purer cousin, flint. Like flint, it was used by stone-age peoples to create projectile points, knives, and other tools, plus ornamentation.

Amorphous Silica - A noncrystaline Quartz

Amorphous Silica - common properties: Luster: Vitrious to resinous, & opalescent.
Moh’s hardness: 5 ½ ~ 6 ½. Density: S.G. 1.8~2.3. Transparency: Transparent to opaque.
Cleavage: None. Fracture: Conchoidal, Crystal system: Amorphous.

Precious Opal: This is the most valuable form of Quartz and it is famous for the magnificent fiery play of colors emanating from within its’ depths. This gemstone is literally, a hardened gel of silica and water. This gel is composed of tightly packed silica spheres. It is the refraction of light off of these spheres that causes the play of color, known as “fire”. If the water content in the gel dries out, the stone will loose its’ “fire”, turn chalky, and become more brittle.

Fire Opal: A variety of Opal, and Precious Opal, primarily from Mexico. The prominent colors are fiery, reds, oranges, and yellows.

Common Opal: Usually a dull white or gray and called “potch”, but when it is found in any of a myriad of colors, it is quite beautiful and can be valuable. Pure Opal is white, but impurities can produce any color. Examples of beautiful common opals in various colors, are: Peruvian Opal – pinks, blues, sea greens, browns, whites, etc.; African Opal – green, red-brown, honey, gold, white, clear, etc.

Although, Opal is found in most parts of the world, major deposits are found in Australia, Mexico, Peru, Ethiopia, Brazil, Africa, and U.S.A.

Moss Opal: White common Opal with dendritic manganese inclusions.

Opalite: Impure, colored varieties of common opal.

Wood Opal: AKA. Opalized Wood. A petrified wood where the original wood structure is replaced, cell-by-cell, with opal. Usually found in a variety of colors, and can include Precious Opal.

Found in Australia, Idaho, Nevada, Oregon, Arizona, Utah, and Washington.

Opal Fossils: Innumerable prehistoric plant and animal species have been preserved in the form of fossils. The fossil replacement material can be Calcite, Chalcedony, Pyrite, and Opal, amongst others. In the Opal fields at Lightning Ridge, Australia, they have discovered a large variety of opalized fossils. These fossils include remnants of ancient plants, mussels, snails, crustaceans, fish, turtles, plesiosaurs, crocodiles, pterosaurs, dinosaurs, birds, and mammals, plus pinecones, microscopic protozoan, and coprolites. The fossils are usually exact replicas of plant, shell or bone material.

Most specimens at the Ridge are a combination of pseudomorph and replacement fossils. Although the transformation to silica has destroyed biomolecular evidence, marrow tissue, blood vessels, capillaries and nerve channels may be perfectly preserved. If the Opal is transparent, these features are clearly visible below the surface in opalised bones. Occasionally, bone specimens seem to show remnants of tendons or cartilage. A surprising aspect is the opalisation of delicate materials like leaves and even dinosaur skin. Many pieces resemble coprolites, reptilian armor scutes or heavy scales.

Although, most of the Australian Opal fossils are made of common Opal, there are many formed from precious opal, white and black. I own a precious Opal clam fossil from Coober Pedy, and while I was there, I was shown some beautiful precious Opal belemnite fossils. The belemnite fossil looked like a fiery 3” long tube. The owner wanted thousands of dollars (U.S.) for it.

Opalized fossils, including Opalized Wood, are found all over the world.

Glass: Crystaline Quartz sand is usually the primary component of this man-made product. Technically, glass is an amorphous liquid. The visual properties of the glass can be changed by the addition of different chemicals (lead = leaded glass, or crystal). Different coloring agents added to the mix produce different colored glasses. Today colored glass is swirled in clear glass to produce colored inclusions in the glass (see strawberry and pineapple quartz).

Before I introduce you to Cryptocrystalline Quartz, I want to touch on a few varieties Macrocrystaline Quartz that have undergone transformation by the forces of nature. Their use in jewelry is limited, but significant.

Sandstone - landscape: This beautiful, warm toned, rock looks like a grainy painting of (American) southwest landscapes. When the rounded and angular layers, within the rock, are in tones of red, yellows, browns, and beige, plus dull greens, grays, and black, they can form magnificent vistas.

There are artists who search out large examples of these beautiful rocks. They select their rock, have it slabbed, mark off their image area, and have the rock cut to a usable size. Then the artist signs the landscape, and displays it as a piece of art. Some of these pieces of natural art will sell for high prices.

Jewelry artists seek out magnificent, miniature landscapes. They will cut them to shape and use them in exquisite broaches, pendants, and other pieces of jewelry.

These natural sandstone landscapes are created when sedimentary layers of crystalline quartz sand are naturally cemented together. When the natural cement includes oxides of Iron we get the buff, brown, and red colors. Other colors can be created by the inclusion of various metal salts in the natural cement. This sandstone was created, millions of years ago, by the natural cementing together of layers of quartz sand that had built up under the ocean, on lake and river bottoms, and in sand dunes. The cementing material can be silica, limestone, carbonates, clay, iron oxides, etc.

Fine examples of Landscape Sandstone are found in Salamanca, Spain and the U.S.A.

Dendritic Sandstone: Dark tree, bush, or fern like formations, on the surface of the sandstone. Individual dendrites on the sandstone surface can be exquisite by them selves, as are images of expanses of vegetation. When the dendrites form on the surface of beautiful sandstone landscapes, they can improve the image by creating foreground trees and vegetation that add depth to the image.

Artists and jewelry makers use dendritic sandstone in the same way they use landscape sandstone.

These dendrites are produced when dissolved manganese and/or iron salts seep into cracks in the sandstone. As the liquid dissipates, the metallic salts crystallize within the crack, and form the beautiful, micro-thin, crystalline dendrites. When excavating the sandstone, these cracks will cleave open to expose the dendrites, and hopefully a beautiful image.

Quartzite: This sparkly, dull to shiny, white rock is composed of crystalline quartz sand that has been recombined back to a solid rock. There are two types of quartzite and they are virtually identical. The differences have to do with how they were formed. The first type is Orthoquartzite. It forms when quartz sandstone is cemented with silica. The second type is Metaquartzite and it is formed when quartz sandstone is compressed together by metamorphic forces.

Historically, quartzite has been used in adornment and jewelry since prehistoric times. Currently, quartzite beads are created and prized in Africa.

Quartzite is found in all parts of the world. In particular, it is found as pebbles and cobbles on beaches and riverbeds.

Silica Glass: A natural quartz glass formed by the impact of a meteor or asteroid on quartz sand. A radioactive, natural green silica glass was formed by the impact of nuclear bombs over quartz sand. I have seen, non radio-active silica glass used in artistic jewelry

Fulgurites: A jagged, natural silica glass tube created when lightning fuses quartz sand, usually in a sand dune. A fulgurite is actually a petrified lightning bolt. It is a rare collectable, and rarely used in artistic jewelry.

Now, the introduction the Cryptocrystalline varieties of Quartz.

Cryptocrystalline Quartz
(Microscopically small crystals.)

Cryptocrystalline quartz - (usual) common properties: Luster: Waxy to dull.
Moh’s hardness: 6 ½ ~ 7. Density: S.G. 2.56~2.64. Transparency: Dull to translucent.
Cleavage: None. Fracture: Conchoidal, Crystal system: (Trigonal), fibrous aggregates.

Scientists divide cryptocrystaline Quartz into sub-varieties, based on composition and structure. They include:
Chalcedony – true fibrous cryptocrystaline quartz;
Jasper – an impure, granular form that is composed of chalcedony, quartz, & opal;
Flint & Chert – a cruder, impure, granular form of cryptocrystaline quartz.

Cryptocrystaline quartz is usually formed near the earth’s surface, where pressures and temperatures are low. Hot, silica-laden water percolates up, and fills any opening it can find. The varieties usually form as nodules in lavic bubbles, as seams in cracks or fissures in host rocks, and as botryoidal or mammillary crusts on host rocks.

As the solution cools, and the water borne silica precipitates out of suspension, it forms extremely small, crystals. As these crystalline deposits form, their chemical conditions can go through slow changes that usually affect the color, rate of deposition, and texture of the precipitate, and thus, change the look and physical composition of the resulting rock. When these layers are prominent, the result can be agate or onyx.

Chalcedony (agate), jasper, and even quartz crystals can all be intertwined together in the same rock, confusing the differentiation between the basic sub-varieties, even more. Commercially, today, the names “Agate” and “Jasper” are being used for any form of chalcedony, without regard for their true nature.

All forms of cryptocrystaline quartz tend to be porous and can easily absorb coloring agents. Since ancient times, chalcedony varieties have had colors added. In the past, and currently, chalcedonies have been permanently pigmented (black & blue Onyx). Lately, common, gray-white, chalcedony has been dyed into a myriad of beautiful soft colors with common dyes that usually fade back to gray-white in a short period of time.

Chalcedony: A name commonly used today for any form of cryptocrystaline quartz, but in the narrow sense, it is specifically the bluish, to white, to gray variety, although it can also be brown, black, or blue.

Chalcedony is found all over the earth, and has been used since prehistoric times for weapons, tools, and adornment.

Carnelian: AKA Kornelian. This brownish-red to orange, translucent to opaque chalcedony gem was probably named for the kornel cherry it resembles. Iron is the coloring agent, and heating can enhance the color. Carnelian has been used since prehistoric times for weapons, tools, and adornment.

Most carnelians today, are really dyed and heat treated agate. To check if the carnelian is real, just hold the stone up to a light. If you see stripes, it is probably treated agate. If you see a cloudy distribution of color, it is probably carnelian. Either way, they are virtually the same thing, and both are varieties of chalcedony.

Major deposits of carnelian are found in Brazil, India, and Uruguay

Chrysoprase: This green to apple green to grass green gemstone is the most precious variety of chalcedony. The green color is produced by nickel, and this gemstone is found around nickel ore deposits. Sunlight and heat can cause the color to fade. It is said that by placing the stone in a dark, humid area, the faded color can be recharged.

Chrysoprase is usually found in small nodules and cracks in serpentine deposits. Although many people prefer a pure green gemstone, other people like chrysoprase with inclusions of the brown matrix in which it is found.

Found in Australia, Brazil, India, Madagascar, Zimbabwe, Tanzania, Frankenstein (Poland), the Urals of central Russia, Kazakstan, U.S.A. (Arizona, California, and Oregon).

Lemon Chrysoprase: A yellow-green gem. It is a Magnesium carbonate mineral, but not a quartz gem.

Prase: A rare, less vivid green form of chalcedony. The color is created by inclusions of the mineral actinolite. Prase is found in Eastern Europe and in the states of Delaware and Pennsylvania in the U.S.

Chrome chalcedony: AKA Mtorolite. A naturally green chalcedony found in Zimbabwe, Africa.

This is the conclusion of our Quartz series.