Malachite is always a shade of green.
Amethyst is a type of Quartz that is purple due to iron and aluminum impurities.
Pyrite is a metallic mineral that is a bright, brass yellow color, and found in a variety of forms.
Pyrite can be found in a variety of forms, from massive accumulations to various crystal forms. The most recognizable is the cubic form, which often have striations running across the surface. It has a hardness of about 6–6.5, actually making it softer than quartz; additionally it can also be brittle and break in an uneven or somewhat conchoidal manner. However pyrite is heavier than many common minerals, with a specific gravity of almost 5. When pyrite is exposed, it can react with both oxygen and water, resulting in the formation of acid.
Pyrite can be found in massive forms, sometimes readily seen along surfaces of rocks, such as this rock outcrop of metamorphic gneiss located in Canada.
There are several minerals that are very similar to pyrite. Marcasite is what is called a ‘polymorph’ of pyrite, meaning that while it has the same chemical formula, it is structurally different, and thus a different mineral. Chalcopyrite has copper added to it (CuFeS2), and is also a brassy yellow color, but is softer and lighter than pyrite (can you think of why this might be?). Bornite has even more copper and added sulfur (Cu5FeS4); you may know this mineral as “peacock ore” as when it tarnishes it turns from a copper-red to iridescent blues and purples.
Peacock ore is a technically called Bornite, and has a similar chemical composition to Pyrite. When it oxidizes these amazing colors can form as a result!
Pyrite has been used in the past for use in fire arms due to its ability to spark when struck. In more modern times it has been used to produce sulfur dioxide or sulfuric acid for industrial use, though this is not as common as it used to be. Pyrite in recent years has become available for use as beads or pendants for jewelry work. Care must be taken when using it – be sure to NEVER store it completely sealed without something to absorb moisture. Many a collector has stored pyrite in air tight containers or zippy bags, only to find a slushy mess a few months later. This is because the pyrite will react with the moisture and air trapped with it, resulting in the disintegration of it and the production of acid in its place (hence if you come across this situation handle with care!)
Rarely, fossils can undergo a process called "replacement", where the fossil is replaced with a mineral (while keeping its original form); in this case an ammonite found in Russia has been replaced with pyrite.
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Pyrite Facts:
Chemical composition: FeS2
Crystal System: Isometric
Color: Pale brass-yellow
Habit: Massive, Crystals (often cubic)
Fracture: Uneven, Slightly Conchoidal
Cleavage: Poor
Luster: Metallic
Transparency: Opaque
Hardness: 6–6.5
Specific Gravity: ~5g/cm3
Streak: Greenish-black
Occurrence: Worldwide
References
Rocks, Minerals, & Fossils of the World by C. Pellant and R. Phillips. Published 1990 by Little, Brown and Co. ISBN: 0316697966
Wikipedia – Pyrite. http://en.wikipedia.org/wiki/pyrite
Mindat – Pyrite. http://www.mindat.org/min-3314.html
Sodalite often appears as a mixture of colors, and rarely found in a solid blue mass.
Many are familiar with the royal blue color of sodalite, however it occurs in a variety of colors including shades of blue, color less, white, light yellow, green, gray, pink, and violet. Hence it can sometimes be difficult to identify sodalite from other minerals. In its commonly sold blue form, one way to distinguish it is its streak. This the color the powder of the mineral leaves when ran across a ‘streak plate’ which is commonly a piece of white porcelain, however in a pinch you can try doing this on a white piece of paper. *Be sure to do this using a ‘fresh’ surface of the stone – trying this with polished surfaces such as what you get with beads doesn’t work – you need to expose a fresh surface of the stone.
The blue/blue+white variety is most often used for creating beads and decoration.
Sodalite is only found in quantity in a few select locations – mainly in Canada, and a few states in the USA, though a few smaller deposits can be found on other continents. There are a few different types of sodalite, one of the more interesting being Hackmanite. This particular form of sodalite has a property called “tenebrescence” which results in the stone changing color when exposed to light! (This same property is used in industry to create those glasses that will darken when exposed to sunlight!)
This mineral can make for some very pretty and unique jewelry!
Sodalite is a beautiful stone today used mainly for jewelry work, and sometimes decoration and sculpture. One story has it that in 1901, the Prince and Princess of Wales (the future King George V and Queen Mary) were presented with a piece of sodalite. The princess loved the beauty of this stone so much that she had tons of it shipped back to England where she used it to decorate the Marlborough house. Years later this mine was renamed the “Princess Sodalite Mine” in her honor.
Sodalite Facts:
Chemical composition: Na4Al3(SiO4)3Cl
Crystal System: Isometric
Color: blue, color less, white, light yellow, green, gray, pink, and violet
Habit: Massive, rarely crystals
Fracture: Uneven, Conchoidal
Cleavage: Dodecahedral (six directions), poor
Luster: Vitreous, Greasy
Transparency: Crystals are transparent to translucent, massive specimens are opaque
Hardness: 5.5-6
Specific Gravity: 2.27-2.33
Streak: White
Occurrence: Worldwide, but most commonly in Canada and the US
Other: Fluorescence
References
Rocks, Minerals, & Fossils of the World by C. Pellant and R. Phillips. Published 1990 by Little, Brown and Co. ISBN: 0316697966
Wikipedia - Sodalite. http://en.wikipedia.org/wiki/Sodalite
Wikipedia - Tenebrescence. http://en.wikipedia.org/wiki/Tenebrescence
Mineral Galleries - Sodalite. http://mineral.galleries.com/minerals/silicate/sodalite/sodalite.htm
Geological Garden gets 4-ton rock. http://newsrelease.uwaterloo.ca/news.php?id=1004
The pretty blue celestine crystals are a favorite among collectors.
Celestine comes in a variety of colors, including colorless, white, yellow, orange, gray, green, brown, and pale blue. It is the pale blue that is most commonly sold both as specimens and as beads. The introduction of celestine in the jewelry market is fairly recent, and can make for some beautiful jewelry. However, care must be taken as it is a soft stone, and can more easily be scratched than harder minerals such as quartz. It is also very slightly soluble (dissolves) in water, so do not expose it to water or moisture for any extended period of time. It is also best not to expose it to the Sun for extended periods if you do not wish the colors to fade.
These blue celestine crystals occur with white aragonite and a few purple fluorite crystals.
The worlds largest geode, located at Crystal Cave, Ohio (refer to previous article on geodes), is made of celestine. It is 35 feet at its widest point, and has crystals as wide as 18 inches across, estimated to weigh 300 lbs. Also of interesting note, there is a micro-organism called Acantharea (radiolarian protozoans) which have skeletons of strontium sulfate (aka Celestine). Celestine has sometimes been mined as a source of strontium, but always in very small quantities.
Crystal Cave, the worlds largest geode, is made up of large celestine crystals.
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Celestine Facts:
Chemical composition: SrSO4
Color: colorless, white, yellow, orange, gray, green, brown, pale blue
Habit: prismatic and tabular, also massive and granular
Fracture: uneven
Cleavage: prismatic and basal
Luster: vitreous
Hardness: 3-3.5
Specific Gravity: 3.9
Streak: White
Occurrence: Worldwide, mainly in the northern US, Europe, and Madagascar
References
Rocks, Minerals, & Fossils of the World by C. Pellant and R. Phillips. Published 1990 by Little, Brown and Co. ISBN: 0316697966
Mindat – Celestine. http://www.mindat.org/min-927.html
Wikipedia – Celestine. http://en.wikipedia.org/wiki/Celestine_(mineral)
Wikipedia – Crystal Cave. http://en.wikipedia.org/wiki/Crystal_Cave_%28Ohio%29
Goldstone is actually a manmade glass that can to some effect resemble natural stone.
Other than knowing that goldstone is created by the precipitation of copper in glass, the process is a fairly guarded secret. It is known that the process is a slow one, and must be created in small batches, hence why it is more valuable than many other glass beads. There are several varieties of goldstone to be found, based on color. The most common is the reddish-brown goldstone, which gets its color from the copper – the glass itself has no color. Another type is the blue/purple color, which does have colored glass to give the blue and purple colors, with sparkles that take on a silver color. The rarest is the green goldstone, which is made with a dark green colored glass and has light green sparkles.
Goldstone comes in several colors: reddish brown (most common), blue, purple, and green (rarest).
Since the actual process of creating goldstone has been kept pretty secret, there is some debate as to how it was initially created. Some say it was discovered in Venice, Italy by the Miotti family, and has since continued to be a desirable element in jewelry work. Myth has it that Italian monks accidentally discovered it centuries ago. It is said that while working on creating glass windows, copper shavings were spilled into the vat of glass. At first they thought the batch was ruined, but the result was this beautiful sparking glass instead! (Sadly, someone has decided to scam people using this myth in conjunction with the misinformation that goldstone is a natural stone, by setting up a “tour” of an old monastery in Italy where people can go in and pick pieces of goldstone up off the ground!)
Goldstone can be manipulated much like natural stone, creating chips, beads, and figures.
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Goldstone Facts:
Chemical composition: Glass and Copper (SiO2 with Cu)
Color: reddish brown (most common), blue, purple, green (rarest)
References
Wikipedia – Goldstone. http://en.wikipedia.org/wiki/Aventurine_glass
Lapidary Digest. http://www.gemcutters.org/LDA/Archive/html%20files/LD029.htm
Copper is mined and has a vareity of uses, particularly as jewelry components.
Copper is a great alternative metal to use in jewelry work and is useful for practicing techniques as it is cheaper than Sterling Silver or Gold filled metal.
Copper has made a popular entrance into jewerly work recently as well. Although a slight greenish tint can occur when wearing Copper, numerous people have no reaction to it or don't wear the jewelry long enough for this to be a concern. Should this occur it can be easily washed off; additionally, some also try to coat the metal to protect both it and the person wearing it such as clear nail polish.
If there's a stone you would like to know more about - drop me a line! Have a mystery stone? Feel free to post a comment about it, including a link to a picture, and it could be featured on this blog!
Copper Facts:
Chemical composition: Cu, plus various alloy compounds
Color: Brown to coppery red
Habit: Branching and dendritic, can be massive
Fracture: Rough
Cleavage: None
Luster: Metallic
Hardness: 2.5-3
Specific Gravity: 8.9
Streak: Red-brown
Occurrence: Worldwide, some of the largest deposits in N. America and the UK
References
A Guide to Rocks and Fossils by B. Busbey III, R. R. Coenraads, P. Willis, and D. Roots. Published 2002 by Fog City Press. ISBN: 1877019518
Rocks, Minerals, & Fossils of the World by C. Pellant and R. Phillips. Published 1990 by Little, Brown and Co. ISBN: 0316697966
Wikipedia – Copper. http://en.wikipedia.org/wiki/Copper
Geodes can come in a variety of shapes, sizes, colors, due to variations in the mineral content. These geodes are all mostly some variety of quartz. The one in the back right is chalcedony, which is a microcrystalline form of quartz. In front of it you can see a nice geode with lovely agate banding around it. To the left of it is one that has pyrite in it - more on this one later. Back and to the left of it is another quartz geode, with little black crystals inside of it. And in the back is a large geode of beautiful quartz crystals.Geodes are found in igneous or sedimentary rock. Cavities form within gas bubbles of lava; the material around the void hardens to form the outer layers of the geode. They can also form within sedimentary rocks, often limestone, that has been dissolved (usually be acids such as carbonic or sulfuric acid). Minerals are carried in by water into the cavities, resulting in the growth of crystals. When the rock surrounding the geode erodes, these geodes are left behind.
This is what geodes typically look like from the outside; often they are a gray or tan to brown color. Sometimes they even sort of look like a brain! Geodes can have many different minerals. Most contain some variety of quartz, including clear quartz, rose quartz, amethyst, jasper, agate, chalcedony, calcite, celestite, pyrite and so forth. Sometimes you even get minerals deposited on top of other minerals. The only way to tell what is inside a geode is to break it apart. There is no easy way of telling what the inside of a geode holds until it is cut open or broken apart, however, geodes from any one locality usually have a more restricted variety of interior mineralization.
Image from inside Crystal Cave, the largest known geode in the world, located in Put-in-Bay, Ohio, USA.Geodes are common in several locations in the United States, including Indiana, Kentucky, Missouri, Utah, and Iowa. Iowa even has the geode as the state rock, and has Geode State Park. The largest known geode was found in 1897 at Put-in-Bay located in Ohio. It is called Crystal Cave, and you can even go on a tour inside this 30 foot deep cave, with crystals as big as 3 feet (1m) wide.
Some creative person decided to fill this geode with pyrite! How can you tell it wasn't like this originally? Well, the pyrite is overhanging the edge of the cavity. Yet it was cut in half - if the pyrite had been there originally, there would be none sticking out beyond where the geode was cut! However its still pretty - just be aware geodes are sometimes modified.
Geodes are used for decorative purposes and jewelry. They are sometimes dyed, so if you see one for sale with very bright colors like neon pinks, blues, and purples, then it has been dyed. As seen in the above picture, other materials are stuck inside that don’t belong there! Sometimes objects are also placed inside, creating little landscapes. Geodes have been used both as slices and cut halves; care must be taken using the slices of geode as they can be somewhat fragile. But what wonderful and unusual jewelry they make!
Using geodes in jewelry work can be a bit tricky, but can have great results!
If there's a stone you would like to know more about - drop me a line! Have a mystery stone? Feel free to post a comment about it, including a link to a picture, and it could be featured on this blog!
Jasper is a varitey of microcrystalline quartz, but with impurities to result in a variety of colors.
Jasper comes in many varieties due to the different chemical impurities, as can also exhibit different ‘patterns’ in the stone due to the environment in which it formed. A number of these varieties have their own names which are purely trade names, not scientific. One of the most common is the red jasper, which is gets its red color from hematite. Autumn jasper often has colors of green, red, orange, brown, and white all mixed together and often speckled in appearance. Kambaba jasper is a green and black jasper that often has swirling patterns, and is sometimes mislabeled as rhyolite. Known as both Kiwi jasper and Sesame jasper, this stone has a spotted pattern of white, blue, and black. Another common jasper is Zebra jasper, which has bands of white and black.
There are many varities of jaspers known by specific trade names. Clockwise from the top is: Kiwi/Sesame jasper, Zebra jasper, Kambaba jasper, and Autumn jasper.
Two of the most sought after jaspers currently are the Ocean jaspers and Imperial jaspers. Ocean jasper, also called Orbicular jasper, forms when Rhyolite (an igneous rock) becomes silicified. In other words, the rock eventually is entirely replaced with silica (aka jasper). Rhyolite itself is silica rich, and as it cools sometimes the silica in the rhyolite can form spheres – hence the pattern commonly seen in Ocean jasper. Imperial jasper comes in shades of green, pink, brown, yellow, purple, cream – the two most sought after being the purple and green Imperial Jasper. It’s a beautiful stone, with rich colors often with subtle flowing patterns.
Jaspers provide a varitey of beautiful stones for jewelry work, such as this green Imperial Jasper.
If there's a stone you would like to know more about - drop me a line! Have a mystery stone? Feel free to post a comment about it, including a link to a picture, and it could be featured on this blog!
Jasper Facts:
Chemical composition: SiO2 + impurities
Color: Many colors
Habit: Commonly massive
Fracture: Uneven and conchoidal
Cleavage: None
Luster: Vitreous
Hardness: 7
Specific Gravity: 2.65
Streak: White
Occurrence: Worldwide, though some varieties are only mined from specific locations (e.g. Ocean Jasper and Imperial Jasper)
References
A Guide to Rocks and Fossils by B. Busbey III, R. R. Coenraads, P. Willis, and D. Roots. Published 2002 by Fog City Press. ISBN: 1877019518
Rocks, Minerals, & Fossils of the World by C. Pellant and R. Phillips. Published 1990 by Little, Brown and Co. ISBN: 0316697966
Mindat – Jasper. http://www.mindat.org/min-2082.html
Quartz is often seen as crystal points, but can occur in other forms such as this egg shaped quartz.
Examples of Quartz inside geodes The variety of color in quartz is due to impurities within the crystal, and a number of these have different names. Chalcedony is a cryptocrystalline (microcrystalline) form of quartz with very small crystals – hence you don’t get the hexagonal crystals but often appears as smooth and banded. Other cryptocrystalline quartz includes agate (multicolor, banded), onyx (like agate with straight bands, multi color or black), carnelian (reddish orange), jasper (opaque, multi-color), aventurine (often with shimmering micas, commonly green), prase (green), plasma (dark green), heliotrope or bloodstone (like plasma but with dark red spots), sard (reddish-brown), and moss agate (has dendritic patterns of manganese).
A variety of quartz, including amethyst, jasper, citrine, carnelian, agate, rose quartz, double terminated quartz, and rutilated quartz.
Other quartz varieties include amethyst, which is a purple color due to the presence of manganese or ferric iron, and is perhaps the most valuable form of quartz as a gemstone. Rose quartz gets its color from traces of manganese or titanium, and can lose its pink color when heated. Smoky quartz is a dark brown color, is caused by irradiation; a very dark brown /black type is also known as morion. Citrine is commonly a pretty yellow or orange color due to inclusions of iron hydrates. Tiger’s eye is a fibrous form of quartz that is typically a yellow-brown color, but with the addition of impurities can appear as other colors.
Rutilated quartz occurs when quartz forms around rutile, resulting in a crystal that has little shoots of rutile running through it. Similarly tourmalinated quartz can form in the same way, though these shoots would appear black.
Quartz can also be rutilated, having golden rutile through it, or tourmalated which has black tourmaline in it. This occurs in quartz veins, where the quartz forms around the rutile or tourmaline. These minerals are essentiall 'trapped' inside the quartz.
If you have a stone you would like to know about, please feel free to leave a request in the comments section. Have a mystery stone? Leave a link in the comments to a picture of it, and it may be featured as a part of this series!
Quartz Facts:
Chemical composition: SiO2
Color: Most common white/clear, but occurs in many colors
Habit: Commonly 6 sided (hexagonal) prisms, also massive
Fracture: Uneven and conchoidal
Cleavage: None
Luster: Vitreous
Hardness: 7
Specific Gravity: 2.65
Streak: White
Occurrence: Worldwide
References
A Guide to Rocks and Fossils by B. Busbey III, R. R. Coenraads, P. Willis, and D. Roots. Published 2002 by Fog City Press. ISBN: 1877019518
Rocks, Minerals, & Fossils of the World by C. Pellant and R. Phillips. Published 1990 by Little, Brown and Co. ISBN: 0316697966
Wikipedia – Quartz. http://en.wikipedia.org/wiki/Quartz
This display at the National Museum of Natural History in the US shows some of the variety of color just within the grossular species. 
Uvarovite is a spectacular green garnet, and is often sought after for jewelry. Garnets are common world wide, particularly in metamorphic rocks such as marble and schist; pyrope garnets are usually associated with igneous rocks. They are abundant in the US, Brazil, South Africa, England, and Australia. Gemstone quality crystals are used in jewelry work, the most common being the red garnets. It is also the birthstone for January. Garnets have also been used as an abrasive for sand blasting, in cutting, and as part of some water filtration units.
Garnets can be found in nice crystal forms, such as the grossular garnets on the left. However the deep reds are a popular color found in jewelry.
If there's a stone you would like to know more about - drop me a line! Have a mystery stone? Feel free to post a comment about it, including a link to a picture, and it could be featured on this blog!
Garnet Facts:
Chemical composition: X3 Z2 (SiO4)3
Crystal System: Isometric/Cubic
Color: Varied – red, green, yellow, brown, black, blue, orange, clear
Habit: Well formed crystals are common, as well as massive and granular.
Fracture: Conchoidal
Cleavage: Indistinct
Luster: Vitreous, Resinous
Hardness: 6.5-7.5
Specific Gravity: 3.4-4.6
Streak: Colorless/White
Occurrence: Worldwide
References
A Guide to Rocks and Fossils by B. Busbey III, R. R. Coenraads, P. Willis, and D. Roots. Published 2002 by Fog City Press. ISBN: 1877019518
Rocks, Minerals, & Fossils of the World by C. Pellant and R. Phillips. Published 1990 by Little, Brown and Co. ISBN: 0316697966
Wikipedia – Garnet. http://en.wikipedia.org/wiki/Garnet
Fluorite can be found in a vareity of beautiful colors including blue, pink, blue-green, and purple.
Fluorite can occur as a variety of colors, including green, blue, purple, pink, yellow, and white. These colors can occur as angular banding, commonly referred to as ‘chevron’ banding. A neat property of fluorite is that it is fluorescent – in fact this is where the term fluorescent came from. When held under UV light, the electrons inside the fluorite become ‘excited’ resulting in their energy level increasing – when they come back down from this ‘excited state’ light is released. Usually in fluorite this will be blue, but other colors are known to occur.
Fluorite can often be found as cubic crystals (left) and a bit more rarely this gorgeous chevron banding (right).
In the United States, the state of Illinois is the most abundant location for fluorite, and is the official mineral of Illinois. This area is often called the ‘fluorspar district’, and was mined until 1995 when the last mine closed – now it’s a popular location for rockhounds to collect specimens. Another famous locale for fluorite is in Castleton in Derbyshire, England. Here there is a unique blue and purple fluorite called ‘Blue John’ and is used for ornamental stone. Fluorite is a popular stone for jewelry work, though care must be taken as it is a ‘soft’ stone with a hardness of 4 on the Mohs hardness scale.
Fluorite makes for a beautiful stone to use in jewelry and ornamental work.
If there's a stone you would like to know more about - drop me a line! Have a mystery stone? Feel free to post a comment about it, including a link to a picture, and it could be featured on this blog!
Fluorite Facts:
Chemical composition: CaF2
Crystal System: Isometric
Color: blue, green, purple, pink, white/clear, yellow, brown, red, black
Habit: Crystals, Granular, Massive
Fracture: Uneven, Conchoidal
Cleavage: Perfect
Luster: Vitreous
Transparency: Transparent
Hardness: 4
Specific Gravity: 3.3
Streak: White
Occurrence: Worldwide, but most commonly in the US and UK
Other: Fluorescence, some specimens may exhibit thermoluminescence
References
Rocks, Minerals, & Fossils of the World by C. Pellant and R. Phillips. Published 1990 by Little, Brown and Co. ISBN: 0316697966
Wikipedia – Fluorite. http://en.wikipedia.org/wiki/Fluorite
Amazonite usually refers to the pale blue to richer blue colors of Amazonite.
Russian Amazonite often refers to the richer green/blue-green variety with white striations.
Amazonite makes for a lovely color to add to jewelry. As pictured in the pendant on the left, it is also sold with a combination of minerals including Pyrite, Tourmaline, and/or Quartz.Wikipedia – Amazonite. http://en.wikipedia.org/wiki/Amazonite
Calcite occurs in a vareity of forms as seen in these samples of calcite.
Calcite can be found in a wide range of color, the most common being white and yellow, but also occurring in shades of green, blue, orange, gray, purple, red, and brown. One way to test for calcite is by using acid, such as very dilute hydrochloric acid; when dropped onto a sample containing calcite it will fizz vigorously. Some have also reported using vinegar, although it produces a weaker fizzing action. [Always use caution with acids regardless of how ‘weak’ or dilute they are.]
Some of the more unusual colors of calcite include blue, green, and peach/orange.
A neat property of calcite is its ability to produce a double refraction. This is best seen in calcite that is in a clear rhombohedral form (at one time specimens like these were called Iceland spar). Calcite is also the main constituent in shells for marine organisms, and found in many fossils. Calcite is said to have been valued by ancient peoples for building material once they realized it could be crushed and mixed with water to form cement and plaster. Calcite is sometimes used in decoration or jewelry, but must be handled with care (if not enhanced) as it is more fragile.
Calcite as it appears in its perfect rhombohedral shape (left) and the very clear optical calcite showing double refraction (right).
If there's a stone you would like to know more about - drop me a line! Have a mystery stone? Feel free to post a comment about it, including a link to a picture, and it could be featured on this blog!
Calcite Facts:
Chemical composition: CaCO3
Crystal System: Trigonal
Color: Commonly white & yellow, also peach/orange, gray, blue, purple, green, red, and brown.
Habit: Crystalline, prismatic, tabular, scalenohedral, rhomobohedral, stalactitic, massive, concretions
Fracture: Conchoidal
Cleavage: Perfect
Luster: Vitreous to pearly
Hardness: 3
Specific Gravity: ~2.7
Streak: White
Occurrence: Worldwide, though the UK is known for very excellent crystals, and optical calcite is collected in Iceland.
References
A Guide to Rocks and Fossils by B. Busbey III, R. R. Coenraads, P. Willis, and D. Roots. Published 2002 by Fog City Press. ISBN: 1877019518
Rocks, Minerals, & Fossils of the World by C. Pellant and R. Phillips. Published 1990 by Little, Brown and Co. ISBN: 0316697966
Wikipedia – Calcite. http://en.wikipedia.org/wiki/Calcite
Wikipedia – Aragonite. http://en.wikipedia.org/wiki/Aragonite
One of the most famous and most photographed geologic sites in the world is the banded ironstone formation.
Specular hematite or specularite as photographed from two different angles.
Most hematite used in jewelry is actually synthetic, often called Hemalyke.
Schiller or Adularescence is what gives Moonstone its 'glow' or 'sheen', which is usually silver or blue.Moonstone comes in several colors, the more common being white, gray, and peach. White Moonstone, with an especially strong bluish sheen, is often called Rainbow Moonstone, and is actually not a moonstone but another feldspar mineral called Labradorite; it is very popular to use in jewelry. The most valuable is the blue Moonstones from Sri Lanka, particularly as there are fewer being found thus driving up prices for this most beautiful of stones.
Moonstone comes in a variety of color, though the more common ones are gray, peach, and white.
Rainbow Moonstone has a lovely blue sheen that is very desirable by jewelry artisans, although the name is a misnomer as its actually a type of Labradorite instead of Moonstone.
