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;
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!
(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
There are three basic forms of
Macrocrystalline, Cryptocrystalline, and Amorphous Silica.
This series will try to explore and describe many of the various
forms of Quartz gems.
(Crystals that can be seen with the naked eye.)
Crystalline quartz - (generally) common properties: Luster:
Moh’s hardness: 7. Density: S.G. 2.65. Transparency: Transparent to
Cleavage: None. Fracture: Conchoidal, brittle. Crystal system: (Trigonal),
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
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
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..
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
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
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 &
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
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
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
Rose Quartz is found in: Brazil; Germany; Madagascar; India; Africa;
Sri Lanka; USA; etc.
-- Included Quartz crystal --
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
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
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
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;
Prase: A.K.A. Emerald Quartz. A rare, leek-green aggregate
Quartz whose color is the result of included hair-like crystals of
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; &
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
Important deposits are in: South Africa (export is
forbidden); Australia, Myanmar; India; Namibia; and California
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
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
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
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
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
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
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
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
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
Zebra Jasper – a black and white striped jasper. (It may not be real
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
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
Amorphous Silica - A noncrystaline
Amorphous Silica - common properties: Luster: Vitrious to resinous,
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
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
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,
Although, Opal is found in most parts of the world, major deposits
are found in Australia, Mexico, Peru, Ethiopia, Brazil, Africa, and
Moss Opal: White common Opal with dendritic manganese
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
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
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
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
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
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
sandstone is cemented with silica. The second type is Metaquartzite
and it is formed when quartz sandstone is compressed together by
Historically, quartzite has been used in adornment and jewelry since
prehistoric times. Currently, quartzite beads are created and prized
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
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.
(Microscopically small crystals.)
- (usual) common properties: Luster: Waxy to dull.
Moh’s hardness: 6 ½ ~ 7. Density: S.G. 2.56~2.64. Transparency: Dull
Cleavage: None. Fracture: Conchoidal, Crystal system: (Trigonal),
Scientists divide cryptocrystaline
into sub-varieties, based on composition and structure. They
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
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
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
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
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
Chrome chalcedony: AKA Mtorolite. A naturally green
chalcedony found in Zimbabwe, Africa.
This is the conclusion of our Quartz series.