AGATE is a form of quartz having submicroscopic grains of cryptocrystalline quartz, called chalcedony, in a massive form, often filling voids as veins or geodes. Agate is often found with color bands due to impurities in the fluids from which the agate is deposited. Agate is usually translucent, sometimes transparent, and has a hardness of 7, but has no crystal structure (amorphous).

There are many types of agates, some of which have become very popular with jewelers.
These include: Blue lace agate, Botswana agate, Brecciated (poppy) agate, Crazy lace agate, Dendritic agate, Fairburn agate, Laguna agate, Moss agate, Onyx, and Sardonyx.

AMAZONITE derives its name from the Amazon River, however it is doubtful that the stone occurs in that region. It is a green to blue-green variety of Microcline, a feldspar mineral. Amazonite is used in jewelry, where it is usually cut into a cabochon form. It is also quite lovely used in carved objects. Because of its color and texture it is sometimes mistaken
for jade.

The color of AMAZONITE varies from green, yellow-green to blue-green, and in some gemstones demonstrates white streaks. Colorado is a well-known locality for crystals of amazonite, and it is also found in Madagascar and Brazil.

Amethyst is a violet variety of QUARTZ, and has a chemical composition of SiO2. Gem quality amethyst is a relatively inexpensive gemstone often used in jewelry. Amethyst mineral specimens, geodes and large cathedrals are prized by collectors. Amethyst occurs in a wide range of purple shades from pale lilac to deep purple. When amethyst is heated, it becomes CITRINE, a yellow or orange variety of quartz.

Ametrine (also known as trystine) is a variety of QUARTZ that displays both amethyst and citrine in the same mineral. Ametrine is mined mostly in Bolivia, with some being found in Brazil and India.

Although ametrine occurs in nature, some ametrine products on the market have been artifically colored by the irridiation or heating of quartz.

AMMONITE–AN EXTINCT SUBCLASS OF THE CEPHALOPOD CLASS OF THE PHYLUM MOLLUSCA (Mollusks). Present-day cephalopods include the octopus, squid and nautilus, which is the closest in appearance to the ammonite. Ammonites ranged in time from approximately 400 million years(Devonian) until about 65 million years.(late Cretaceous). Their chambered shells are found today, while their soft bodies, which occupied the largest and outermost chambers, are gone. The septa, plates which divide the chambers, are highly visible in cut fossilized ammonite specimens.

Ammonites had a tube called a siphuncle, which carried water from outside the shell to the chambers, and was used to propel the ammonite as well as to change its depth in the water. Cephalopods, such as the ammonite, were swimming mollusks, rather than attached (pelecypods) or bottoms dwelling(gastropods) mollusks.

The ammonites showed an increasingly complex pattern of sutures on their shells as time went by. Sutures are the intersections of the septa and the outer shells.

Aqua Aura is created by allowing molecules of pure gold to adhere to the natural electric charge which surrounds quartz crystals. The extremely thin, transparent gold coating breaks light into its spectral colors.

Aqua aura requires no special care to retain its beauty. The gold coating cannot be rubbed or scraped off.

Quartz covered with 24 karat gold.

The name "AQUAMARINE" is derived from Latin meaning "water of the sea." It is a blue or blue-green variety of the BERYL GROUP. Other gem quality varities of beryl are emerald and and precious beryl (bixbite, golden beryl, goshenite, heliodor and morganite). The coloring agent of aquamarine is iron. Dark blue is the most desired color for aquamarine gemstones, and clearer specimens are often heated or irradiated to attain the desired color.

In the United States, aquamarines can be found at the summit of Mt. Antero in the Sawatch Range in central Colorado. In Wyoming, aquamarine has been discovered in the Big Horn Mountains, near Powder River Pass.

Azurite is a copper mineral which has similar origins to malachite, but is more frequently in crystalline form. However, azurite is found less commonly than malachite. Occasionally, azurite crystals are replaced by malachite, known as pseudomorphs. Azurite is characterized by its deep blue color. Fresh unweathered azurite has a vitreous luster.

Brachiopods are know as living fossils since few species are still living today. They were abundant in the Paleozoic Era now the fossils are found in Paleozoic rocks and limestone deposits throughout the world. They decreased in numbers during the Permian extinctions. Brachiopods consist of two part shells or valves that have fossilized. Fossils are found in various shapes and sizes throughout the world.

Cactus Quartz, or Spirit Quartz, was first discovered in 1986 in the Magaliesberg Mountain Range near Pretoria, South Africa. It was called "Spirit Quartz" by the South African tribal medicine men who used them for healing rituals. Cactus quartz is formed by a quartz or amethyst crystal being encrusted by a second generation of smaller crystals grown on its faces. It occurs as quartz, citrine and amethyst, and comes in a wide range of colors, including purple amethyst, violet amethyst, smoky, milky clear and golden citrine.

Calcite is a common rock-forming mineral. It has many industrial uses, such as cement, and is found in many colors. It occurs in many forms of crystals, and in many types of deposits, and has a strong rhombohedral cleavage. An optically clear variety is called Iceland spar, and exhibits strong double refraction, which is when a ray of light enters the mineral, it is divided into two rays that diverge. It is too soft to be used as gem material, but many beautiful crystals have been collected the world over.

Carnelian is a reddish variety of chalcedony. Chalcedony is a mineral mixture of quartz, moganite and another silica mineral. Agate is another form of chalcedony.

Prevalence:
Worldwide - Australia, Austria, Botswana, Brazil, Canada, China, Czech Republic, Egypt, France, Germany, Hungary, India, Japan, Mozambique, Peru, Poland, Portugal, Romania, Russia, Slovakia, South Africa, Sri Lanka, Switzerland, UK, Ukrane, USA

The cathedrals on our Website are true wonders of nature - they come from a series of basaltic flows in the southern Brazilian state of Rio Grande do Sul. They are mined by hard rock mining methods, then cleaned cut and polished by local craftsmen.

Cathedrals are large GEODES formed in large gas bubbles in basaltic lava.

Cathedrals are graded for sale by exterior size and shape; crystal size, color and perfection; and overall appearance. Also, the appearance of other minerals such as calcite and quartz which form after the amethyst, may add to the value.

Go to these Rock Professor pages for more information on AMETHYST or CITRINE.

Celestite got its name from the celestial blue color in its crystals. Celestite is distinguished by its high specific gravity (density), tabular crystals that resemble barite, relative softness and transparency to translucency. Found in sedimentary deposits, veins and cavities, it is often associated with minerals such as gypsum and dolomite. Most fine specimens today come from Madagascar.

Charoite has only recently come on the market. It was discovered in Siberia, Russia in 1947, but only became known internationally in 1978. Most believe the stone was named for the nearby Chara River.

Charoite has a lovely dark purple color with a swirling, fibrous appearance, and is sometimes chatoyant. The material is a silicate of potassium, calcium and sodium.

Chrysocolla is a secondary mineral found in oxidized zones of copper deposits. It is abundant in the southwestern United States as well as in numerous areas worldwide. It is sometimes confused with turquoise, but it is softer. It is cryptocrystalline and is typically found in masses or fracture fillings.

Citrine is a light yellow to yellowish-brown variety of QUARTZ. Natural citrine is colored by trace amounts of ferric hydroxide. Most of the citrine on the market is actually heat-treated amethyst or smoky quartz.

As in other varieties of quartz, citrine has a hardness of 7, a specific gravity of 2.65, and chemically, is SiO2. It has a vitreous luster and belongs to the hexagonal crystal system.

When amethyst is heated to approximately 500-600 degrees C, a yellowish-brown citrine color is produced. Not all amethyst responds in like fashion. Most of the Brazilian citrine on the market comes from the Irai region of Rio Grande do Sul.

COPPER is a basic element (Cu) and is the eighth most abundant metal in the Earth's crust. It occurs as a native metal and in a some 160 compounds, some of which are azurite, malachite, chrysocolla, chalcopyrite and bornite. The alloys of copper are also important such as bronze, an alloy of tin and copper; and brass, an alloy of zinc and copper.

Being malleable and ductile, copper is a good conductor of heat and electricity and has many industrial uses, among which are electric cables and wires, plumbing, heating, roofing and construction. The Egyptians are believed to be the first to create bronze, which ushered in the Bronze Age.

Leading producers of copper are Chile, the U.S. and Indonesia. Three U.S. states are very rich in copper deposits: Arizona, New Mexico and Utah. Copper is mined in at least 63 countries, including Russia, Canada, Zambia, Poland, China, Uganda, Nicaragua, Australia and Mexico.

Most of the native copper on our site come from the Keweenaw Peninsula, Michigan.

The copper specimen pictured to the bottom left is referred to as "float copper", copper ore which was ripped loose from the earth's surface by a glacier, then traveled with the glacier to its ultimate destination and remained behind when the glacier melted.

COPROLITES are the fossilized droppings of ancient creatures. The name translates as "dung stone" from the Greek words "kopros" meaning "dung" and "lithos" meanings "stone." To the eye of the observer, many of these fossils look as if they were dropped yesterday, but fortunately the original material has been replaced with minerals and there is no smell.

Coprolites are trace fossils as opposed to body fossils, in that they are not part of the body of the creature that left them. Other examples of trace fossils are foot prints and burrows. Since coprolites often contain plant material or remains of other creatures, they are important to scientists as they record the diet, feeding behavior and habitat of dinosaurs and other prehistoric life.

In 19th century England, coprolites were mined on an industrial scale for use as fertilizer due to their high phosphate content.

Many of the coprolites on this Website come from the Eocine period (35-55 million years ago) and were dropped by turtles or sloths.

DUGWAY GEODES Juab County, Utah
These unusual single and multi-cavity geodes are Utah's version of Thunder Eggs. Within a rhyolite exterior shell, druzy and crystalline quartz-lined cavities were formed by silica-rich fluids seeping into cavities formed in the rhyolite.

Some geodes have up to 5 or 6 crystal pockets, some are connected to each other, and some have small islands of banded rhyolite "floating" between the cavities. The geodes are dug from sediments formed by the ancient Lake Bonneville, and range from tiny up to about 1 foot in diameter.

Eudialyte is a fairly rare mineral. It has a poor crystal habit, so when crystals are found, they are prized by collectors. However, it is very attractive when polished for use in jewelry. It has a deep red color in a matrix of black, gray and white.

The Kola Peninsula, Russia, is the locality which produces much of the eudialyte seen on the market today. Eudialyte is a source of zirconium.

FIRE AGATE is a gemstone variety of chalcedony (quartz family) where layers of heated iron oxides and silica line cavities in rock. Light passing through the many thin layers gives a reddish, fiery glow, from which the name fire agate is derived. The agate has a hardness of 7, and if carefully cut and polished, can make a glowing, multicolored gemstone.

FLUORITE is not only a much-used industrial mineral, but is also highly sought after by collectors for its many colors, translucency, association with many other minerals, and cubic crystals. Chemically, fluorite is calcium fluorite, and is often found in hydrothermal vein deposits along with other minerals such as calcite, sphalerite, barite, galena and quartz. Large deposits of fluorite were mined in the Cave-in-Rock District of Illinois until the 1990's, and lesser amounts have been mined in many areas of the U.S., where it is often used as a flux in steel production. Other large deposits have been mined in Canada, England, China, and many other areas.

Fluorite is often found that fluoresces under untraviolet light, most commonly blue, and the name "fluoresce" stems from the mineral name. Physically, fluorite is a soft mineral (H=4), and is easily identified by its colors, hardness, strong cubic cleavage and cubic crystals.

Fluorite is found in many colors, including purple, blue, green, yellow, pink, red, white, brown, and black. It is sometimes zoned, where outer layers have different colors and/or shades of colors. In the southern Illinois deposits, small chalcopyrite crystals were found within the fluorite crystals. Some of the massive Chinese deposits exhibit beautiful multicolored banding, and many carvings and beads have been made from this material.

The garnet group of minerals is a group of chemically and physically similar minerals. They are as follows:

Grossularite is a calcium aluminum silicate. It can be colorless, gray, many shades of yellow and green, also pink, red, brown and black.
Pyrope is a magnesium aluminum silicate. Colors are blood-red, dark red, purplish-red, orangish-red and pinkish -red.
Spessartite is a manganese aluminum silicate, and can be orange, reddish-orange, red, reddish-brown, yellowish-brown and brown.
Almandite is an iron aluminum silicate, Almandine is typically a deep red-violet, also can be red, brownish-red and brownish-black.
Andradite is a calcium iron silicate. It occurs in yellowish-green, green, greenish-brown, gray and black.
Uvarovite is a calcium chromium silicate; the color is dark green.

The uses of garnet are as gemtones and abrasives. Because they are hard, lack cleaveage and fracture into sharp, irregular pieces, garnets are an excellent abrasive. As a gemstone, they highly refractive, hard, have beautiful colors, and are transparent. However, possibly due to their abundance and widespread use, they do not fetch a high price as a gemstone.

GEODES are spheroidal to eccentric-shaped rocks formed when minerals either enter or are trapped in openings or voids inside preexisting rock material. In volcanic rocks, fluids and gases often remain inside air pockets in the lava. During and after cooling, these fluids, from the outside in, fill the cavity with various successions of agate and quartz layers, often ending in open cavities with inward-facing quartz crystals. Other geodes may be formed by cavities formed by dissolved organic material, fractures in the rock, or by pockets caused by dissoved mineral material. These geodes will often have tapered layers that lead to in "inlet", where the filling solutions entered the cavity.

Rarely, a geode will be partially filled in the center by a horizontal sequence of layers inside the concentric bands, ending in a flat surface. This is a gravity filling of the cavity with materials probably under less pressure, ending when there are no more fluids. You can tell which way was "up" when the geode formed.

Colors within the geodes are caused from elements, such as iron, that are carried in the solutions. Most geodes are composed of agates, a member of the quartz family, although some geodes are formed of calcite, usually in limestone pockets.

Halite is the mineral form of sodium chloride, NaCl, commonly known as rock salt. It is easily distinguished by its taste. Halite is found in many current evaporative deposits such as near Salt Lake City, Utah and Searles Lake California in the U.S., where it crystallizes out of evaporating brine lakes. The mineral is typically colorless to yellow, but may also be light blue, dark blue, and pink depending on the amount and type of impurities.The color in pink halite is due to the organism Halo bacterium that lives in the concentrated brine.

The name hematite is derived from the Greek word for blood (haima) because hematite can be red. Hematite is mined as the main ore for iron. Some uses of the mineral are as a polishing compound (rouge), coloring pigment for bricks and tile, and in jewelry.

SPECULAR HEMATITE is a variety of hematite with a blue-gray color and bright
metallic luster.

Kunzite is a lilac colored gem variety of the mineral Spodumene, which is a lithium aluminum silicate. Kunzite is found with Morganite and in lithium rich pegmatites, often as very large crystals. It is deeply striated vertically.

Another variety of spodumene is the pale green hiddenite, found notably in North Carolina.

The name, KYANITE, is from the Greek "kyanos" meaning blue. It is an aluminum silicate and is a metamorphic mineral. Kyanite is a polymorph with two other minerals: andalusite and sillimanite. (A polymorph is a mineral that shares the same chemistry with another mineral, but that has a different crystal structure).

The mineral forms blue fibrous blade-like crystals, often with a darker blue color near the center and a lighter color towards the outer edges of the blades.

Kyanite is a beautiful gemstone when faceted, but it is difficult to process as it has two different hardnesses depending upon direction. Parallel to the length of the crystal, kyanite has a hardness of 5. At right angles to this direction it is 7.

Labradorite is a semi-translucent, gray gemstone with a beautiful play of colors called labradorescence. As one turns the stone one can see flashes of blue, violet and green and sometimes orange and yellow.

Labradorite is named from the locality where it was first found: Labrador, Newfoundland. Another variety, spectrolite, is found in Finland.

LAPIS or LAZURITE is a rare and prized mineral; used in both jewelry and carvings. It was first mined thousands of years ago in northeastern Afganistan, where the richest lapis still is found today.

Lapis occurs mostly as lapis lazuli, a mixture of lazurite and lesser amounts of pyrite and white calcite. The color of the highest quality material is a rich, deep blue, with no calcite visible. Lower grades (today often called "denim lapis"), have more of a spotty look, with patches of lazurite in a matrix of calcite.

The stone has a medium hardness, and prices vary in today's market from $20/lb. for low-grade rough material up to several hundred dollars per pound for the very highest quality. Lapis is also mined in Chile, Siberia, and is found in minor amounts in many countries, including the U.S.

LAZULITE is a different mineral, chemically as well as in its occurence, but also is bluish in color. It is distinguished from lapis by the absence of pyrite as well as calcite.

LARIMAR is a rare blue variety of pectolite (calcium-sodium silicate) found only in the Dominican Republic, in the Caribbean. Since being officially discovered in 1974 by Miguel Méndez and Peace Corps volunteer Norman Rilling, the beautiful stone has been extracted from volcanic tubes or chimneys where it was formed. Pectolite is found in a variety of locations, however none have the volcanic blue coloration of LARIMAR which owes its beautiful color to copper.

Miguel Méndez named the new mineral LARIMAR for his daughter Larissa and for
"mar"- Spanish for "sea".