The Rock Professor
The Rock Professor


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 Crystal
(Microcline-Albite)
Image attributed to
Rob Lavinsky
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.


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 shells: originally composed of aragonite; after fossilization, the shell
becomes calcite.
Ammolite: some of the original shells retained their mother of pearl nacre over the centuries, which during fossilization, was chemically transformed into an iridescent material called ammolite (aragonite with varying
mineral impurities).
Localities: include Russia, England, Morocco,
U.S., Madagascar.
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.


Brachiopod Fossil
Image attributed to
Mark A. Wilson (Department of Geology, The College of Wooster).

Image by Roger Weller,
Cochise College

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.


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.


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.

Image courtesy of:
www.pasty.com/copperrange/today.htm
Native Copper Mass located at:
Henry Ford Community College,
Dearborn, Mi.♦ Chemistry: Cu, elemental copper
♦ Class: elements
♦ Color: copper colored with weathered specimens tarnished green
♦ Luster: metallic
♦ Transparency: opaque
♦ Fracture: jagged
♦ Crystal system: Isometric
♦ Moh's hardness: 2.5-3
♦ Localities: Michigan and Arizona,
Canada, Chili, Peru,
Germany, Russia, many parts
of Africa and Australia
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.
Photo by Roger Weller,
Cochise College
Coprolite deposited by small mammal
30 M years ago.
Completely silicified. Oregon
Most coprolites are composed chiefly of calcium phosphate, along with minor quantities of
organic matter.
Coprolite is a variety of phosphorite (which is a variety of apatite).
Coprolite deposits range in age from the Cambrian period to recent times.
Coprolite's color depends on the type of soil and minerals in which it was buried.
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.

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.


Chemistry: Calcium fluoride (CaF2) ♦ Class: Halides ♦ Crystal system: Isometric ♦ Moh's hardness: 4 ♦ Transparency: Transparent to translucent ♦ Luster: Vitreous ♦ Color: Purple, blue, green or yellow; also colorless, reddish orange, pink, white, brown ♦ Cleavage: Perfect in 4 directions forming octahedrons ♦ Fracture: irregular and brittle ♦ Fluorescence: Blue or more rarely green, white, red or violet and may be thermoluminescent, phosphorescent and triboluminescent ♦ Localities: China, Germany, Austria, Switzerland, England, Norway, Mexico, and both Ontario and Newfoundland in Canada. It is found in many states in the US, notably Illinois.
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.
Class: Nesosilicates ♦ Crystal system: isometric ♦ Color: occurs in all colors except blue ♦ Luster: vitreous to resinous ♦ Transparency: transparent to opaque ♦ Cleavage: none ♦ Fracture: conchoidal, somewhat brittle ♦ Moh's hardness: 6.5 - 7.5 ♦ Localities: USA, Australia, China, India, Russia, Turkey, Alaska
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.
Composition:
may include
quartz crystals,
amethyst crystals,
agate, chalcedony,
jasper, calcite,
dolomite, celestite.Prevalence:
U.S., Brazil,
Namibia, Mexico
Cathedrals, amethyst:
large to very large
geodes lined with
amethyst crystals
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.


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.

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

Chemistry: aluminum silicate, Al2SiO5 ♦ Crystal system: Triclinic ♦ Habit: columnar, forms columns ♦ Habit: Fibrous crystals ♦ Moh's hardness: 4 to 5 in one direction 6 to 7 in another direction ♦ Transparency: Transparent to translucent ♦ Luster: Vitreous to pearly ♦ Color: Blue principally, but also white, gray or green. Color is often not consistent throughout the crystal ♦ Cleavage: Good in one direction parallel to the flat blade face ♦ Fracture: Brittle ♦ Localities: Brazil, Virginia, North Carolina, Georgia, Switzerland, Russia, Serbia, India and Kenya.
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 named from the locality where it was first found: Labrador, Newfoundland. Another variety, spectrolite, is found in Finland.
Chemistry: Sodium calcium aluminum silicate sulfur sulfate ♦ Class: Silicates ♦ Subclass: Tectosilicates ♦ Group: Both the Sodalite and feldspathoid groups ♦ Associated Minerals: Calcite, pyroxenes and pyrite ♦ Crystal system: Isometric ♦ Moh's hardness: 5-5.5 ♦ Transparency: translucent to opaque ♦ Luster: dull to greasy ♦ Color: brilliant blue with violet or greenish tints ♦ Cleavage: Poor ♦ Fracture: Uneven ♦ Localities: Afghanistan; Chile; Russia; Italy; USA - California (San Bernardino Mountains and Ontario Peak) and Colorado (Sawatch Mountains).
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".


The Willamette Meteorite, discovered in the Willamette Valley, Oregon, is now on display at the American Museum of Natural History in New York City.
Meteorites are intriguing to scientists as a rare source of material evidence of the universe beyond the Earth.
There are three main types of meteorites. The most abundant are stone meteorites which are primarily made up of silicate minerals such as olivine, pyroxene and feldspar. As their name implies, iron meteorites are mainly composed of iron but also contain a significant amount of nickel. The rarest of the three are the stony-iron meteorites. They are a mixture of stony and metallic materials.

Travertine is found in many parts of the world including the US. Massive deposits in Pakistan are also being used for cutting and carving into many beautiful objects. Click her for more information on PAKISTANI ONYX.

Moldavite is a type of TEKTITE, a natural glass rock with rounded or irregular shapes and pitted or wrinkled surfaces. The Impact Theory states that TEKTITES may be fused glass that formed during an impact of a meteor with layers of rock on the Earth's surface. The TEKTITE contains properties from both the meteor and the Earth crust at the impact site.
MOLDAVITE is a jewelry-quality Tektite, stemming from a meteorite that collided with earth approximately 14.7 million years ago and created the Ries crater in Germany. Moldavites are found in a "strewnfield" centered around Moldavia in former Czechoslovakia.
Rainbow Moonstone Specimen Image attributed to controverscial.com
Localities: Sri Lanka, Burma, Brazil, India, Madagascar, USA

Chemistry: Potassium aluminum silicate hydroxide fluoride ♦ Class: Silicates ♦ Group: micas ♦ Crystal system: monoclinic ♦Luster: vitreous to pearly ♦ Color: white, silver, yellow, green and brown ♦ Transparency: transparent to translucent ♦ Fracture: uneven ♦ Cleavage: perfect in one direction producing thin sheets or flakes ♦ Moh's hardness: 2 - 2.5 ♦ Localities: India, Pakistan, Brazil and many USA localities.
MUSCOVITE was once commonly used for windows. The Russian mica mines that produced it gave muscovite its name (it was once widely known as "Muscovy glass"). Muscovite is is a high-aluminum member of the mica family of minerals, all known for the property of perfect basal cleavage; cleavage layers can be easily peeled off into very thin sheets which are quite durable and are not easily destroyed by erosion. Muscovite sheets have high heat and electrical insulating properties and are used to make electrical components.
A common rock forming mineral, muscovite is found in igneous, metamorphic and detrital sedimentary rocks. It is not usually valuable as a mineral speciemen but can be found associated with other valued minerals such as tourmaline, topaz, beryl, almandine
and others.

About Orthoceras
Orthoceras fossile are found in the Saharan desert (Northern Africa).
The name "orthoceras" means "straight horn" and refers to the creature's long, conical shell.
Squids from the Sahara?
In these shells lived Orthoceras, an ancient mollusk whose fossil shells are found and polished in the Sahara Desert of Morocco.
About Orthoceras
Orthoceras fossile are found in the Saharan desert (Northern Africa).
The name "orthoceras" means "straight horn" and refers to the creature's long, conical shell.
Squids from the Sahara?
In these shells lived Orthoceras, an ancient mollusk whose fossil shells are found and polished in the Sahara Desert of Morocco.
Movement & Bouyancy
The siphuncle is a tube which ran the length of the Orthoceras's shell. By filling the siphuncle with water, the orthoceras could then use its muscles to force the water out and propel itself through the water. You can see this jet propulsion in action in the video below which shows a Nautlius found in today's oceans:
Like the Nautilus shown above, Orthoceras used its siphuncle to control bouyancy as well. By controling the ratio of air to water in the siphuncle, Orthoceras could move up and down in the water.
Growth
Orthoceras's soft body lived in the open segment at the end of it's shell. As its body grew, and that part of the shell became too small, a dividing partition called the septa grew to separate the old "home chamer" from the new one. Orthoceras grew as large as 14 feet!
Fossilized
In the Devonian geologic period, some 350 million years ago, these ocean dwellers, reaching a length of over 6 feet, swam in an Ocean which covered the area. After death, their shells were preserved in the black marble where they are found today.
Orthoceras fossils have an iridescent gemlike quality when polished and because of their incredible age and beauty make for unique display pieces and jewelry.

True onyx is a fine-grained siliceous gemstone, but the term has been used for calcareous marble-like layered sediments, technically termed travertine. This onyx is typically deposited from solutions in ground and surface waters, often in caves. The often colorful and banded surfaces, when polished, are sought after for their beauty.
Travertine is found in many parts of the world including the US. Deposits of travertine in Mexico are also being used for cutting and carving into many beautiful objects. Click her for more information on MEXICAN ONYX.

PERIDOT, the gem variety of OLIVINE, is the official August birthstone. Although it occurs in several locations worldwide, it is most famously found on the San Carlos Indian Reservation in southern Arizona, where 80-95% of the world supply of peridot is produced.
Olivine is composed of two minerals, and ranges from magnesium-rich (fayalite) to iron-rich (forsterite). It has strong birefringence, which means when you look into the gem you will often see a doubling of the facet edges and you can see a doubling of the inclusions as well.

Petrified wood: The name comes from the Greek "petro" or "rock", and refers to wood that has been turned to stone. The process of petrification preserves parts of ancient trees in fossil form. When the wood becomes buried under sediment, mineral-rich water flows through the sediment and replaces the cells' structure with minerals, producing a very good stone copy of the original piece of wood. The predominant minerals in petrified wood are silicates, such as quartz.
It's quite wondrous to examine a piece of petrified wood, knowing that it represents part of a hugh forest existing millions of year ago.



Formed in the seams between black shale and coal 300,000,000 years ago, these pyrite dollars do not appear to be fossils, but an aggregate of tiny pyrite crystals.
Today, they are collected by coal miners in Randolph County, Illinois. As the Illinois coal mines are shut down one by one, these specimens will become more and more rare.

Of all the minerals, quartz is closest to a pure chemical compound and has constant physical properties. Crystals are often terminated by a hexagonal pyramid. Quartz is the most common rock-forming mineral on the planet. It is extremely resistant to weathering. It breaks down into sand grains which often form sedimentary rocks.
Cryptocrystalline varieties of quartz include agates and jaspers. Colored varieties of quartz include AMETHYST, CITRINE, AMETRINE, ROSE QUARTZ, SMOKY QUARTZ and
milky quartz.

Chemistry: Manganese Carbonate (MnCO3) ♦ Class: Carbonates ♦ Group: Calcite Group ♦ Crystal system: Trigonal ♦ Moh's hardness: 3.5 - 4 ♦ Transparency: Transparent to translucent ♦ Luster: Vitreous to resinous ♦ Color: Red to pink, sometimes almost white, yellow and brown ♦ Cleavage: Perfect in three directions forming rhombohedrons ♦ Fracture: Uneven ♦ Other characteristics: Pink and white banding in massive forms ♦ Localities: Sweet Home Mine American Tunnel mines, Colorado; Montana; New Jersey; Arizona and California, USA. Also found in Argentina, Peru, Kazakhatan; Romania; England; Germany; Namibia; Mexico; South Africa; Canada and many other localities from around the world.
RHODOCHROSITE is a sought-after, colorful mineral. Earlier considered as gangue or waste rock to be removed to get at the valuable ore, rhodochrosite was thrown aside and buried in districts such as Leadville, Colorado. Its lower quality ore is sometimes processed for its manganese content in places such as Argentina.
Most noticeable features are its rose-watermelon color in its purest form, its relatively soft(H=3) hardness, and its solubility in dilute acids.
In many areas including Colorado and Peru, rhodochrosite is found as rhombohedrons in crystalline form, associated with numerous other minerals, such as pyrite, quartz, tetrahedrite and fluorite. Argentinian rhodochrosite is better know for its banding, stalactitic forms, and its great beauty when cut, carved and polished. Lesser quality material can be paler red or even reddish tan in color.

RHODONITE is named after the Greek word for rose, rhodon.Chemically, it is manganese silicate. Its color is usually pink but it can range to dark pink and even to brown. Rhodonite is distinguished from another pink manganese mineral, rhodochrosite, by its greater hardness (5.5 to 6) and by the presence of black streaks of manganese oxide.
Rhodonite typically comes in massive, coarse and fine granular aggregates. Because of its attractive color and black streaks of manganese oxide, rhodonite is often carved into cabochons, beads and carvings.


RUBY is the red variety of corundum, the second hardest natural mineral (9.0 on the Mohs scale of mineral hardness). Sapphire is the non-red variety of corundum and is generally thought to be blue, although it exists in nearly any other color. A very small amount of chromium gives corundum a pink color. Larger amounts produce stones that are a deep traffic light red, and are known as rubies.
The ruby is considered one of the four precious stones, together with the sapphire, the emerald, and the diamond
Chemistry: Titanium oxide, TiO2 ♦ Crystal: Tetragonal system ♦ Color: reddish-brown, red, yellowish, bluish, violet, black ♦ Luster: Adamantine ♦ Transparency: transparent to opaque ♦ Fracture: subconchoidal to uneven ♦ Moh's hardness: 6 to 6.5 ♦ Localities: Minas Gerais, Brazil, Swiss Alps, USA
and some African localities.
Rutile is one of the five forms of titanium dioxide (TiO2) found in nature. Titanium is a metal used for high tech alloys because of its light weight, high strength and resistance to corrosion.It derives its name from the Latin rutilus, red, in reference to the deep red color of some specimens when viewed by transmitted light..
Rutile has among the highest refractive indices of any known mineral and also exhibits high dispersion. Small rutile needles present in gems are responsible for an optical phenomenon known as asterism. Asterated gems are known as "star" gems.
One of the crystal forms that it takes is that of slender needles (acicular) embedded in large quartz crystals A beautiful stone produced by large inclusions of golden rutile needles in clear quartz is called rutilated quartz. Rutile can also form its own interesting and beautiful mineral specimens.

SANDSTONE is a sedimentary rock composed of sand-sized grains of quartz and feldspar.The spaces between grains may be empty or filled with either a chemical cement of silica or calcium carbonate or a fine-grained matrix of silt and clay particles. Sandstones often form in layers in environments where large amounts of sands can accumlate such as beaches, deserts, flood plains, and deltas.
Sandstones are often used as building stones, and have importance to geologists as indicators of erosional and depositional processes.

Composition: Calcite (the yellow centers), Aragonite (the brown lines) and the bentonite clay (outer grey rock). Occasionally the fossil or some of the fossils which started the formation of the rock is noticeable in the rock ♦ Localities: Utah, New Zealand, worldwide.
Utah Septarians are found near Zion National Park in Southern Utah. They are a beautiful rock that started their formation approximately 150 million years ago when the gulf of Mexico reached what is now southern Utah. Volcanic eruptions killed the sea life and they became trapped in the sediment and formed mud balls.
The ocean receded and the balls were left to dry and crack.
The ocean returned depositing more shell life above them. As this decomposed, calcite from the shells was carried down into the cracks of the mud balls, and calcite crystals formed. A thin wall of calcite was transformed into aragonite dividing the bentonite clay (shale) exteriors from the calcite centers. Because of this dividing wall (septum in Latin) the geodes are called Septarians.

Image credited to: http://www.calvertmarinemuseum.com
CARCHAROCLES MEGALODON
Miocene - 15 million years old Evidence
of its existence:
Fossilized teeth and some minor bones

Smoky quartz is a variety of QUARTZ. The brown, black or smoky gray color is due to exposure to radiation - either natural or artificial.
Smoky quartz is used as an inexpensive gemstone, and is a popular material for carved objects such as spheres, figurines, pyramids, etc.

Sodalite is named for its sodium content. It is a dark blue semiprecious mineral of the feldspathoid group. It has a hardness of 5.5-6 and a specific gravity of about 2.3, making it lighter than quartz.
Brazilian sodalite commonly occurs with veinlets of calcite. Fairly rare, sodalite is also found in Canada and Russia. Sodalite is one of the common constituents of lapis lazuli.

A member of the quartz species, tiger eye is a mixture of chalcedony and the fibrous silicate mineral riebeckite.
Tiger eye includes the colors of yellow or honey, red and brown. Most of the time, these colors are either in lines or bent. It is found in many areas of the world, notably South Africa and Australia

TOPAZ is a common gemstone that has been prized for centuries for its hardness, clarity, and beauty. Mineral collectors are attracted to its well-formed crystals. Topaz is a silicate mineral of aluminum and fluorine, and is one of the hardest minerals in nature. Crystals have been found in sizes reaching several hundred pounds.
Pure topaz is colorless and transparent; typical topaz is white, yellow, pale gray or reddish-orange, blue brown. Orange topaz, also known as precious topaz, is the traditional November birthstone. Imperial topaz is yellow, pink or pink-orange. Many brown or pale topazes are treated to make them bright yellow, gold, pink or violet colored. Blue topaz rarely occurs naturally, and colorless, gray or pale yellow and blue material is often heat treated and irradiated to produce a darker blue.
Chemical Group: Silicate ♦ Group: Tourmaline ♦ Crystal forms: Trigonal system ♦ Color: black, brown, dark blue, colorless, pink, red, green, blue and even multicolored. Crystals frequently contain two or more colors ♦ Luster: Vitreous ♦ Transparency: Transparent to opaque ♦ Fracture: Conchoidal ♦ Cleavage: Poor ♦ Moh's hardness: 7.5 ♦ Localities: Brazil; The USA from Maine, New Hampshire, South Dakota, California.
The tourmaline group refers to a number of related species and varieties of minerals. Tourmaline is a complex crystalline silicate containing aluminum, boron, and other elements, and is used in electronic instrumentation and, especially as a gemstone in its green, clear, and blue varieties.
Although tourmaline has been known since ancient times, it was only imported by the Dutch from Sri Lanka in 1703. The name "tourmaline" is derived from a Sinhalese name, "turamali," meaning "stone with mixed colors."
Follow the links below to read about some of the varities of TOURMALINE.
SOME VARIETIES OF TOURMALINE: DRAVITE, INDICOLITE, REBELLITE, SCHORL, SIBERITE, VERDELITE, ELBAITE, WATERMELON TOURMALINE

all continents.
Bisbee Turquoise Image courtesy of R.Weller/Cochise College
Turquoise is a stone used in ancient jewelry and artifacts, having been mined since at least 6000 BC by early Egyptians, and has been in fashion ever since. The name comes from a French word, "turquoise" which means Turkish, from which country Persian material passed on its way to Europe. Turquoise is a secondary mineral found often in the weathered zone of a copper deposit.
The finest turquoise comes from Iran, but beautiful specimens are also found in the southwestern US.
Because natural turquoise is often very porous and unstable, several processes have been developed to make the material saleable. In STABILIZATION, epoxy and plastics or water glass are impregnated under pressure into the unstable stone. In RECONSTITUTION, small fragments of turquoise material are powdered and then rebonded to form a larger
solid stone.
About Orthoceras
Orthoceras fossile are found in the Saharan desert (Northern Africa).
The name "orthoceras" means "straight horn" and refers to the creature's long, conical shell.
Squids from the Sahara?
In these shells lived Orthoceras, an ancient mollusk whose fossil shells are found and polished in the Sahara Desert of Morocco.
Movement & Bouyancy
The siphuncle is a tube which ran the length of the Orthoceras's shell. By filling the siphuncle with water, the orthoceras could then use its muscles to force the water out and propel itself through the water. You can see this jet propulsion in action in the video below which shows a Nautlius found in today's oceans:
Like the Nautilus shown above, Orthoceras used its siphuncle to control bouyancy as well. By controling the ratio of air to water in the siphuncle, Orthoceras could move up and down in the water.
Growth
Orthoceras's soft body lived in the open segment at the end of it's shell. As its body grew, and that part of the shell became too small, a dividing partition called the septa grew to separate the old "home chamer" from the new one. Orthoceras grew as large as 14 feet!
Fossilized
In the Devonian geologic period, some 350 million years ago, these ocean dwellers, reaching a length of over 6 feet, swam in an Ocean which covered the area. After death, their shells were preserved in the black marble where they are found today.
Orthoceras fossils have an iridescent gemlike quality when polished and because of their incredible age and beauty make for unique display pieces and jewelry.