Minerals

Rarest of the Rare: Unique Gemstones of the World

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Alexandrite Mineral
Alexandrite (variety of chrysoberyl)

In all the naturally occurring substances, gemstones catch our attention the most. Due to their color, shapes, sizes and textures, gemstones are intrinsically rare and always an eyecatcher. And among all the elite and rare stone types, there are some which are considered as the rarest due to their scarcity of nature.

Let’s find out some details about these gemstones that are the rarest of the rare.

Alexandrite: Emerald by Day, Ruby by Night

Named after the Russian tsar Alexander-II, Alexandrite belongs to the family of Chrysoberyl family. It was first found in the Ural Mountain range in Russia in early 18th century. Due to some digression from Chrysoberyl minerals, it became one of the rarest gemstones on the face of the earth. Alexandrite is famous for exhibiting hues of emerald and ruby when seen in the presence of light and darkness respectively.

When it shines under different light sources, it appears with different shades of green, magenta and blue which clearly indicate that Alexandrite possesses splendid color features. The impurities of iron, titanium and chromium are supposed to be the reason why it stands alone among all the other Chrysoberyl gemstones.

Tanzanite: A Gift from Foothills of Mount Kilimanjaro 

This gemstone belongs to the family of zoisite gemstones with blue color. The rarity of this stone can be understood by the fact that the only known deposit of this stone is found in the foothills of Mount Kilimanjaro in Northern Tanzania. Therefore, this zoisite gem is even named after the country.

The bluish-purple stones are found and mined in decades, and therefore it is considered rarer than diamonds. Tanzanite also exhibits different hues under different crystal orientations and light conditions.

Red Diamonds: A Rare Tale of Romance

The combination of red color and diamond stone can be the ultimate gesture of love. Red diamonds are considered to be the fanciest and rarest diamonds. Unlike other fancy diamonds which get their color from different impurities, diamonds get red hue due to a rare bend in its atomic structure known as plastic deformation. There are very few red diamonds in the world (some estimates suggest that only 30 diamonds exist with such color formation).

Grandidierite: Madagascar’s Another Natural Offering

Grandidierites are extremely rare gemstones only found in very few places such as Madagascar, Sri Lanka and Namibia. They were first discovered in Madagascar in the early 19th century by a French mineralogist and named after Alfred Grandidier who is thought to be the first authority on the natural history of the region.

Grandidierite comes in bluish green color patterns, shades which come from the tinge of iron impurities in it. They come in orthorhombic crystal structures. The typical rare Grandidierite appears completely transparent.

Poudretteite: An Exquisite Pink Gem

Poudretteite was first discovered in Canada and named after the family which operates the quarry from which this stone was discovered. Even after more than 50 years, it can only be found in two locations in Canada and Myanmar which makes this gemstone incredibly rare.

The color of Poudretteite depends on the optical phenomenon in which different the color appears when observed at different angles. However, Poudretteite shows light pink and purple hues mostly. Manganese is the color giving element present in Poudretteite, so the color saturation depends on the amount of Manganese present in the stone’s crystal structure.

Benitoite:  A Californian Rarity

Benitoite is a rare gemstone that is extracted from the only and limited deposit near San Benito River in California. It was discovered in 1907. Benitoite comes in blue and purple shades and glows like blue chalk when put under UV light.

Due to its unavailability, Benitoite is not used as a typical gemstone in jewelry items. It is almost impossible to find in the open market and is usually part of rare gem collections.

Musgravite: Distinctive among all the Taaffeite

Musgravite is a rare oxide gemstone belonging to the family of Taaffeite gemstones. Musgravite was first discovered in the Musgrave Range of South Australia. It is very difficult to differentiate them from all the other Taaffeite stones and only an expert can do this. Musgravite exists in grey, mauve, grey purple and light olive green shades.

Minerals

Opal: A Precious Stone with a World of Colors

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Coobe Pedy Opal Doublet Mineral
Coober Pedy Opal Doublet Mineral

Due to its exuberant display of color, opal has often been compared with erupting volcanoes, galaxies and fireworks. A stone exhibiting such grandeur inherently appears mystic and mysterious. And we humans are always intrigued and fascinated by such characteristics. Therefore, opal comes in an elite category of stones that have always been appreciated and revered the world over.

What is an Opal?

The opal stone is classified as mineraloid, a mineral-like substance that doesn’t possess the characteristics of crystalline structures. Opal is an amorphous form of silica which displays a mix of various colors giving it its enhanced enchantment quality. The colors are borne out of the chemical and physical conditions in which the stone is formed.

Most common opals have green and white hues, while black opals are considered to be the rarest. Let’s look into the history of opal to know how this gemstone has been perceived over time.

Historical Journey of the Opal

Opal-53714

The Opal became mainstream with its discovery in South Australia in the 18th century. However, anthropology tells us that opals were in use way before this discovery.

An opal artifact was discovered from a cave in Kenya which dates back to 4000 B.C. According to anthropologists, these artifacts were brought over from Ethiopia.

Apart from that, opal is also depicted in many ancient paintings as a part of ornaments and jewelry. In ancient Europe, Hungary was the origin of opal mining and it is believed that Spanish soldiers introduced this stone to the rest of the world in the 16th century.

Name’s Origin

The historical significance of opal can also be authenticated by the origin of the name ‘Opal’.

    • According to some references, the name opal is derived from a Sanskrit word ‘Upala’ which means ‘precious stone’.
  • Many historians associate the word opal with ancient Rome where two languages were dominant, Latin and Greek. A Latin word ‘Opalus’ means ‘precious stone’ is also thought of as the origin of the name, while the Greek word ‘Opallios’ meaning ‘to see a color change’ is also considered to be a strong contender for the origin of the word Opal.

It is quite evident that whichever origin story you want to buy, the characteristics of opal have always been linked to magnificence.

Types of Opal

Opal sterling silver bracelet

Opal is categorized into different types according to its optical density and colors. There are numerous types of opals according to their appearance, however, we will discuss the ones that are found commonly and are more popular among all the different types.

Fire Opal: They are mostly mined from Western Australia and contain the background color combination of yellow and red with an overall semi-transparent appearance.

Black Opal: Opals are called black due to less transparency which makes their appearance darker. Black opal exhibits a beautiful play of color which makes them one of the most attractive and popular opals out there.

Boulder Opal: This type of opal is basically housed in the fractures of a stone in the form of a vein-like meshwork. These opals are mostly mined along with their host stone so that the opal remains in its natural state.

Common Opal: Common opals have the highest opacity and do not exhibit any play of color. However, common opals can be used in ornaments due to their lustrous appearance.

Gem Therapy with Opal

Gem therapy has been practiced in a plethora of cultures around the world. Although not scientifically proven, anecdotal evidence suggests that gems do have healing powers. With that said, some health benefits that might be associated with opal are:

      • Fire opal is thought of having healing power for blood-related diseases. Its psychological benefits include getting rid of laziness and depression.
      • Black opal has therapeutic benefits for reproductive disorders. By wearing black opal people can also get rid of the stress that comes with those reproductive disorders.
      • White opals are considered very effective for people who have been experiencing neurological disorders.
    • People who are facing sleeping disorders and have frequent nightmares can wear almost any kind of opal stone. Opal is known to relax and therefore, help you sleep.

Zodiac Association of Opal

Opal is considered as the gemstone for the month of October in the Gregorian calendar. It is said to be a suitable gemstone for all those zodiac signs that are ruled by Mercury. People with zodiac signs of Cancer, Libra, Pisces and Scorpio might want to wear opal for its potential benefits.

Minerals

Emeralds: A Part of Ancient Religious and Cultural History of The World

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red diamond 3d rendering
Red Diamond Emerald

Since ancient times, the Emerald has caught the interest and fascination of humans. Like many other gifts of nature found in lush green shades, real emeralds are also found in stunning green color. There are other green gems such as peridot and tourmaline but none are as famous, beautiful and rightfully expensive as emeralds. In this article, we will try to shed some light on the historical significance of the stone. Let’s start with its name origin and some ancient history.   

Emerald’s name origin

Historians are agreed on the fact that the word ‘Emerald’ is the distorted form of a Greek word ‘smaragdus’ which means ‘green’.

Trace back of emerald in the history

The first mining of emerald was reported in the ancient Egypt dating back to 300 BC. In Egypt, emerald was revered as a precious gemstone.  Cleopatra, the last ruler of Ptolemaic Egypt considered the manifestation of beauty, was fond of emerald and it is used as part of many of her royal adornments.

History also suggests that Roman were also fond of this magnificent gemstone. According to the writings of famous Roman naturalist Pliny the Elder, in ancient Rome people stared into emerald to relieve tediousness and exhaustion.  

In the following discussion, we will try to look into the importance of emerald in different cultural and religious symbolism.

Emerald: Equally loved by ancient gods

In many religious beliefs, offering emerald to the spiritual deity results in different rewards for the people. For instance, Hindus were the belief that people who offer emerald to the god Krishna become high in heaven and god rewards these generous offerings with the knowledge of soul and eternity.

There is another historical trace of people offering emeralds to their gods.  A Spanish historian from the 16th century AD, who had extensively researched on the north of South America, also hinted about the emerald offering of the natives to their gods. According to him, people used to burn emeralds and gold before the depictions of the Moon and Sun which are considered the highest divinities.

Emerald used as a rewarding gift to gods implies that not only humans but gods were also fond of this gemstone.

 

Emerald: A stone embedded in the breastplate of Aaron

The breastplate of Aaron, which is discussed in the Old Testament, had different gemstones embedded in it. Scholars are still debating the type of those gemstones because revision to the original text has changed the names and categorization of the stones. Apart from that, the linguistic changes through the course of time have also altered the names of different gemstones.

It has been cited that a greenstone was used in the breastplate of Aaron. It could be the real green emerald, green feldspar or any other green stone but historical indications are stronger towards the use of emerald. Emerald began to be mined near the ancient site of Nubia, Egypt before the era in which the breastplate got made.

The Peruvian goddess made of emerald

In the 15th century, when Spanish kingdom was roaring around the South America, people of the city of Manta in present-day Peru used to worship a goddess named Umina. The goddess was made of an emerald of the size of an ostrich egg. It was displayed to the public only on feast days by the priest.

According to their dogmatic belief, followers can worship the goddess by only bringing her daughters. Small size emeralds were called the daughters of the Umina. When the city was captured and conquered by the Spaniards, they found plenty of emeralds there however they failed to trace the emerald goddess Umina.

Spaniards also waste many of these precious gemstones in order to determine their originality. They smashed emeralds on anvil because they were of the thought that original emerald is the hardest gemstones and it can withstand this smashing.

Emerald Symbolism embedded in depiction of mystic and mysterious cities

There are many tales and folklore in India which talks about the mysterious cities and forts with walls, facets and entire temples made of gold and other precious elements. There are paintings which depict these cities and their features. According to the pictorial depictions of those wealthy cities, leaves of plants and trees have dripping emeralds and rubies.  

From the above discussion, it is quite clear that emerald has always been an important part of different historical religious and cultural reference spread all across the world.

 

Minerals

Zircon: From Gemstone to Pigment

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Zircon gem in red

Photo by simply – yayimages.com

Zircon is a mineral compound composed of the elements zirconium and silicon. Zircon is commonly found in nearly every type of rock formations all around the world. Zircon has been used as a gemstone for millennia. Even though zircon comes in different colors but the most sought after is colorless zircon due to its close resemblance with diamonds, thanks to its fine dispersion and brightness.

Name and history of zircon

Zircon faces chronological injustice because most of people know it as an imitation element due it its extensive use as a low-cost diamond substitute in the beginning of the 20th century. However, the stone is naturally found in many different shades. Even the origination of the name ‘zircon’ indicates that the other colors of the mineral were equally popular in the past.

Name origin of zircon

There are two popular theories regarding the name origination of this mineral stone:

  • Some historians think that ‘zircon’ is derived from the Arabic word ‘zarkun’ which translates to vermilion or cinnabar, both represent different shades of red.
  • Other historians are of the thought that zircon is borrowed from the Persian word ‘zargun’ meaning gold colored.

With zircon’s natural occurrence in a wide variety of color shades, either of the name origination can be true.

A prized stone during medieval times

Different variants of zircons held an important place during the middle ages. People believed that these stones had the ability to repel evil spirits. Possessing zircon was associated with good fortunes and wisdom.  

Important ornamental stone of Victorian era

Zircon became widely popular during Victorian era. Many jewelry specimens of the time were fitted with rare blue variants of the gemstone. A famous gemologist of the time, George Kunz was known for his fondness of zircon. He even proposed the change in name of the stone to highlight its vivid characteristic.

Geology of the stone

Igneous rock formations that have undergone the process of metamorphism usually host zircon gemstone. They are also found as an accessory mineral in granite deposits. Most of this zircon goes unnoticed because its aggregate is present in very small size dispersed in a larger volume of the given ore.  

Gem-grade variety of zircon can be found in the soil and sedimentary rocks. Due to their high resistance to grazing and chemical reactions, they remain to keep their shape and structure even when the rock formation around them undergo erosion. Therefore, there are certain billion-year-old deposits of zircon as per their carbon dating. The bigger the cut of zircon, the better it would be to be used as a gemstone.

Gemstone zircon

Even in modern times, zircon gemstones are used in many jewelry items. Most of the famous choices of zircon gemstone are brown, red and yellow and treated variants of green and blue. We have already discussed that colorless zircons are used as the low-cost diamond substitutes. The other in-demand type of modern times is blue zircon.  

Perfect fit for pieces of jewelry

Due to its greater value of hardness on the Mohs scale (7.5) and good cleavage grading, it is suitable to be used in different ornamental items including earrings, brooches, rings, and bracelets. Jewelry items featuring zircon as the primary gemstone can last for many years without losing the sheen and magnificence of the stone.

Industrial and gem-grade mining of the stone

Since the use of zircon is not limited to the domain of jewelry and gems anymore. Industrial use of zircon has also been established with time. Mining of both types of grades is usually done in separate geological sites.  

Gem-grade

Gem-grade deposits of zircon are being mined for centuries from the alluvium deposits located in the far eastern countries of Vietnam, Myanmar, and Cambodia. Sri Lanka is also famous for the mining of gem-grade zircon.  

Industrial-grade

Now more mining of the stone is done for the sake of its industrial uses. Australia tops the chart for mining zircon for its industrial uses. Brazil, China, and Kenya also have some noteworthy land and marine alluvial deposits of industrial-grade Zircon.

Due to its high-temperature resistant characteristic, zircon is used as a refractory lining that is installed inside furnaces and kilns. By converting zircon minerals into zirconium dioxide at extremely high temperatures, it gets into an amorphous form which is then used as a pigment in different industrial and manufacturing processes.  

Minerals

Ammolite: A Marine Fossil Gemstone

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Ammolite are gem-grade fossilized shells of ammonites. They are known to have spectacular display of sparkling colors in the presence of reflective lights. Different variants of ammolite produces different spectrum of colors; some only reflect one or two colors. These fossilized remains are considered gemstones because they can easily contend the exquisiteness and color strength of established gemstones such as opals and labradorite.

Anatomy of Ammolite

When dissecting the anatomy of this colorful gemstone, one comes to know that ammolite are thin gleamed coverings of ammonite fossils. It should be noted that not all ammonite fossils have ammolite as their coverings. Two species of this extinct marine molluscs are festooned with this organic gemstone. Most of the present day ammolite deposits are found along the riverside of St. Mary in Alberta, Canada.  

Geological History of Ammolites

The host fossil of ammolite, ammonite was present in the waters as a living species nearly 70 million years ago. As their extinction started, the shell of dead ammonites fell to the bed of the seaway and gradually covered with mineral sediments resulting in the formation of gem-quality ammolites.

Ammolite: From Its Original Form to Gemstone

Transforming journey of ammolite from its original fossil form into a gem-grade entity is an interesting one. In the first step, the slender shell of ammonite fossil is removed from its dark shaded base. Since most of the ammolite strips are so delicate to handle therefore they are not subjected to any further processing to enhance the texture and color of the gemstone. Instead, ammolite receives the stabilization treatment. There are few steps involved in the process of stabilization:

    • The fragile specimen of ammolite is reinforced by adding thin block to its back. Usually darker color shale slabs serve this purpose
    • To protect the surface for which ammolite is known, covers of clear transparent minerals are used. Thin covers of spinel and quartz are used so that the surface of ammolite can be protected without affecting its beautiful natural display.

There is another relatively less used method to stabilize ammolite in which the specimen is soaked with an epoxy solution. Rare cuts of ammolites don’t require stabilization and can be used in jewelry in their indigenous form.

Quality Determination of Ammolite and its Uses in Ornamental Items

Apart from their size, there are few other characteristics of ammolite that determine its quality as a gemstone.

  • Ammolites that display more than one glowing color
  • Ammolites that display the phenomenon of iridescence from various angles
  • Ammolites with color bends that are not broken up by gaps are also considered very precious. Gaps are formed ammolite surfaces due to fractures and the inclusion of other minerals

Ammolites that fulfill all these three requirements are then cut and used in different type of jewelry. Capping or transparent covering of the stones is done as per the customer’s requirement. For instance, people who want to have the best and more natural view of ammolite will prefer less dooming. On the other hand, some people like this dooming because it enhances the visual character of the stone.

Ammolites that are totally uncapped or covered can be used in jewelry items such as earrings, pins, and brooches that are less likely to face abrasion.  

Historical Significance of Ammolite in Different Cultures and Religions

In Hinduism

Ammonites found in the fossil sediments of Gandaki River in Nepal usually show golden luminescence and have been used to show the characteristics of Vishnu and his chakra. This attribution of the stones earned itself veneration from Hindus.

In Native America

To the Niitsitapi nation of Native America, ammolite and other fossil stones are associated with an abundance of resources, healing and good fortune.

In Chinese Culture

The believers of the ancient Feng Shui philosophy recommend ammolite as the stone used to cure financial problems. Ammolite is also named after a mythological Chinese beast ‘Qilin’ and hence called Qilin or Kirin Stone. In Chinese tradition, ammolite is also attributed to traits of longevity and non-violence.

It is interesting to see that the same stone is revered in different geological locations and demographics for different reasons. However, it can be inferred that this shared reverence from different cultures and religions is there due to ammolite’s unique iridescence.

Minerals

Extraterrestrial Gemstones

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Extraterrestrial Gemstone

Extraterrestrial objects and beings have been both fascinating and frightening to human beings for centuries. Among them, the ones that have fascinated us are extraterrestrial gemstones.

These stones or rocks are made of very rare metals and minerals and possess a great deal of significance for collectors and geologists. The rock and stones are fragments from extraterrestrial objects that landed on the earth or they were created due to the impact of meteorites.   

What Actually Are Extraterrestrial Gems?

These are meteorites whose impactites are small enough to be used as gems. But that is not the only condition for any extraterrestrial object to be classified as a gem. They should look attractive and pleasing to the eyes as well. Here are a few interesting facts about them:

    • Sometimes, meteorites contain more than two metals, like an alloy. They can be used as extraterrestrial ornaments and gems. For instance, alloy meteorites of iron and nickel are cut and polished into beautiful-looking objects.
    • Meteorites with peridot crystals embedded in them can also be cut into the shape of beautiful gems.
    • Meteorites are rich in silicate are also shaped and polished into the form of cabochons.  

Rare yet Inexpensive

There is no doubt that these ET specimens are very rare in their existence, yet they are not as expensive as some of the popular gemstones. There are two major reasons for this contradiction:

    • Many people are still unaware of this phenomenon where meteorites can be transformed into beautiful gemstones.
    • There is no proper meteorite gemstone market. There is no supply chain for such gemstones and even those that is available in the market are not reliable enough.

Types of ET Gemstones on the Basis of Demand

Not all ET stones are equally sought-after by the people who are interested in collecting and researching such species:

    • Stones that can be used in the same condition in which they fall from the sky are the most expensive type of ET gemstones. Scientists, collectors and jewelers, all want to get their hands on ‘as found’ ET stones.
    • ET stones with the best gem quality are also expensive and used by jewelers to make some limited edition ornamental designs.
    • ET stones with smaller sizes and low quality are usually treated as collectibles.

There are some famous ET gemstones and rocks that have captured the human imagination and have been put to different uses.

Desert Glass

These ET stones are a type of natural glass found in the desert, which has formed as a result of a meteor impact in the area. The glass is created from the silica abundantly found in the desert sand.

There are a few sites all over the world where desert glass can be found. The most popular subtype of this ET stone is known as Libyan Desert glass. Fragments of this desert glass are found in the eastern Sahara Desert.

Desert Glass of King Tutankhamen

The pendant from the pre-BC era shows that desert glass has been used by humans for thousands of years. King Tutankhamun, an Egyptian pharaoh of the 18th Dynasty buried with ornamental items containing desert glass. It shows that ancient Egyptians put this meteor stone in very high regard. The pendant found in the Tomb of the Egyptian King has desert glass as its centerpiece.

Popular for Metaphysical Properties

Even now, desert glass is used for its metaphysical properties. It is thought to have a great mystical power to strengthen your willpower. According to chakra energy principles, the golden yellow color of the glass vibrates in the band of solar plexus chakra which is associated with the willpower of any living body.

Moldavite

Moldavites are formed due to meteorite impacts in southern Germany. They are dull green fragments of meteorites that are considered gem-grade stones. In alternative medicine, moldavites are very popular due to their healing powers for the emotional and physical being of an individual.

Beware of Fake Moldavites

With its supposed health benefits and gem-like appearance, this ET stone has always been in demand. Due to the imbalance of demand and supply, people started to make fake moldavites from glass. Beware of these ‘glass moldavites’ and buy the original ones from a reliable meteor and mineral collector.

Small Meteorites: Used as Earrings

Small and distinctive shaped meteorites are also used by some to make hipster earrings by drilling a hole or with the help of wire wraps.  

 

Minerals

Corundum – Parent Mineral of Ruby and Sapphire

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Corundum Mineral StonePhoto by Epitavi – yayimages.com


Corundum is a mineral found in many metamorphic, sedimentary and igneous rocks. It is aluminum- based rock-forming mineral. Pure corundum ore exists in colorless form. The mineral gets its color majorly from iron and chromium impurities. Some other mineral impurities such as cobalt, nickel, and vanadium can also be found in the deposits of corundum. The mineral is known to possess high levels of hardness, therefore, it can easily be found in crystalline form in many different colors.

Even though corundum has been used by humans in different shapes and forms for centuries, the revolution in modern mining history of corundum happened when a geologist W.F. Ferrier pointed to the large deposits of corundum in Canada in his survey report in 1896. In a few years, the mining of corundum started in the communities of Ontario, Hastings colony and Carlow. Now corundum, both in natural and synthetic form is used for many purposes.

People know corundum by sapphires and rubies

People are familiar with this mineral through the gemstones of ruby and sapphires. Both of these precious stones are the variants of corundum. Finer grades of corundum in red hues are called rubies while the ones with blue shades are known as sapphires.

Physical properties of corundum

Corundum comes in the top three hardest minerals along with moissanite and diamond.  It is assigned with that hardness of 9 on Mohs scale. They get recognized by their distinctive physical properties. They possess high specific gravity and definite hexagonal crystalline structure. They also have a great tendency to cleave along stressed areas.

The history associated with the name ‘Corundum’

Most historians agree to the fact that the word ‘Corundum’ is derived from the Sanskrit word korund or Kurundum. Another fable associates the name with an ancient district of Karund in the state of Orissa, India. The deity of the region is Manikeswari, which literally means ‘goddess of rubies or corundum’.  This claim was also substantiated by the fact that the karund district was known for the deposits of the ruby gemstone.

The occurrence of corundum in Nature

Corundum can be found in many different geological settings and in all those rocks that are rich in aluminous instead of silica. Syenite, nepheline syenite and pegmatite, all of these igneous rocks contain corundum as their primary mineral. It is also found in metamorphic rocks derived from aluminous and carbonate sediments. Marble, schist and other products of regional metamorphism also contain corundum.

Some of the naturally occurring marble deposits contain gem-quality of vibrant colors and clarity. Due to its relatively inert nature and hardness, it is able to survive the extremes of weather and can be found in different alluvial deposits. Most of the higher grade corundum is obtained from the clay beds of different river deltas.  Word’s famous alluvial deposits of corundum are located in Cambodia, Sri Lanka, Afghanistan and India.

Corundum hardness: best suited for abrasives

The hardness of corundum makes it the best contender for abrasives for many industrial uses. Corundum is first crushed into smaller particles which are then processed to produce same-sized granules. The final product is used in different ways for the purpose of abrasion. It is used to make polishes, sandpapers, grinding wheels and other grinding media.

However, with more innovation and precision in the manufacturing process, some disadvantages of natural corundum started to appear. The particles of corundum are usually small and irregular in their sizes – this means the quality needed in the making of many products is not necessarily met.

Synthetic corundum, on the other hand, has consistent physical properties. It is made of calcined bauxite. Corundum in the form of emery rock has also been used as an abrasive in many industries. It is a granular rock rich in corundum, spinel, magnetite and hematite.

Corundum as a gemstone

Even though the use of corundum as an abrasive has declined in recent years due to the availability of better options, no one can take the place of corundum in the world of gem and jewelry because two of the ‘big four’ minerals are variants of corundum.

Diamond, ruby, sapphire and emerald due to their historical significance and aesthetic appeal are the four most sought-after gemstones in the world.

Minerals

Lapis Lazuli – a Heavenly Blue Rock Gemstone

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Lapis Lazuli Stones
Photo by richpav – yayimages.com

Lapis lazuli appears as a mineral, but according to geological classification, it comes under the category of metamorphic rocks. It is a blue rock gemstone that has served many purposes throughout the history. The rock of lapis lazuli is composed of many different minerals and its color is the result of the presence of blue silicate mineral called lazurite. Some other minerals such as white calcite and crumbs of pyrite are also part of the mix of lapis lazuli.

Origin of the Name

The name of this rock gemstone has its origin in Latin and Persian languages. ‘Lapis’ is a word from Middle Latin which means ‘a stone’ and ‘Lazuli’ is a genitive of ‘lazulum’. ‘Lazulum’ has been derived from a Persian word ‘lazhward’ meaning ‘blue’.

History of the Rock Mineral

Egyptians’ Obsession with Lapis Lazuli

The history of lapis lazuli is very fascinating because it has its roots in the pre-BC era. In ancient Egypt, this stone was considered to be one of the most prized tributes and rewards. Some of the oldest mines in Egypt date back to 4000 BC and interestingly, are still active sites of lapis lazuli mining.

It is referenced as sapphire in the Old Testament and thought to be one of the twelve stones embedded in the breastplate of the High Priest. Clothes of royalty and pastors are dyed with this rock gemstone to distinguish them from those of ordinary people. The golden coffin of the Egyptian king, Tutankhamen, was ornamented with lapis lazuli. The stone — due to its ultramarine hue —  is considered very important since it contrasts perfectly with the arid desert hues of the region.

In medieval Europe, lapis lazuli was considered a part of the heaven’s sky. It was used to repel evil spirits and considered sacred to get the blessings of the spirits of wisdom and light.

Geological Occurrence of Lapis Lazuli

Lapis Lazuli is formed when stones like marble and lime go through the process of metamorphism. During the process, the lazurite takes its place in the host rocks in the form of layers and stripes with other mineral additions to take the shape of lapis lazuli.

A rock must have a peculiar blue color and one-fourth of its part must be made of blue lazurite to be considered lapis lazuli.  The addition of calcite and pyrite are responsible for white and gold layers in the stone.

How Lapis Lazuli Rocks get Refined?

Many of the specimens of mined lapis lazuli are dyed in the finishing process before going into the market as sculpture base, ornaments and gemstones. They are dyed with blue color to remove the white shade created by the presence of calcite.

Uses of Lapis Lazuli

In Jewelry

Lapis lazuli is commonly used as an ornamental stone in pins, earrings and pendants. Lapis lazuli has a Mohs hardness of 5, which makes it unsuitable for jewelry items that face more abrasion such as rings and bracelets.

Lapis Lazuli: a Pigment

Lapis lazuli has been used as a high quality pigment for a long time. To make pure rich blue pigments, the rock is treated with soft acids to remove the minerals of calcite and dolomite that adulterate the blue color of the stone. The final product of lapis-rich pigment is then mixed with oils and other mediums to be used as high quality paint.

The Starry Night: A gift of Lapis Lazuli Pigment

For more than 100 years, the art and culture all around the world have been fascinated and inspired from the master strokes of Van Gogh in his one of the best artwork “The Starry Night”. The painting has a distinctive vivid blue backdrop which is there because The Dutch maestro used ultramarine lapis lazuli pigment for this oil on canvas painting.  Some other historical paintings of medieval times are also based on the pigment of lapis lazuli.

In alternative medicines, lapis lazuli is still used as the stone for its benefits of different healing energies.

Minerals

Topaz: A Mineral Made of Silica and Fluorine

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Photo by Epitavi – yayimages.com

Topaz is a silicate based mineral that occurs in different colors and shapes. It is usually formed in Pneumatolytic actions under the earth’s surface when gases pass over hot magma.  According to a research conducted by the University of California, Berkeley, during the final stages of solidification of igneous rocks such as pegmatite and rhyolite, the fluorine-rich vapors convert into crystals to take the form of topaz.

Cavities and fracture of igneous rocks are the usual sites of topaz formation and eventual extraction. The secondary deposits of topaz can be found in pebble sediments of streams with their origin in these igneous rocks.

Properties of Topaz

Topaz is one of the hardest known mineral stones. It possesses a hardness of 8 on the Mohs Hardness scale. Only diamond, chrysoberyl and corundum are harder than topaz given this criterion of hardness.

Most of the naturally occurring topaz stones are colorless or possess a milky tinge. Rare ones can be found with shades of orange, pink, red, blue and purple. These rare topazes are the ones used for ornamental purposes.

Topaz is fragile and easy to break. This contrasts sharply against the reading it takes on Mohs Hardness scale. The reason behind their fragility is a distinct basal cleavage that slices perpendicularly to the long axis of the crystal. The long axis of topaz is formed when it is grown unhindered in nature to take the shape of orthorhombic crystals.

Origin of the Name

There are two popular theories regarding the origin of the name ‘Topaz’. Many historians believe that the name comes from a Greek island in the Red Sea called Topazios. The interesting fact about this name origin is that, the island never produced topaz. Deposits of peridots, which were extracted from the island, were mistaken for topaz before the development of the subject of modern mineralogy. Another popular theory associates the origin of the stone’s name with Sanskrit word of topas or tapaz, meaning ‘fire’.  

Historical Significance of Topaz

The ancient Greeks were of the thought that wearing topaz offered strength. They believe that topaz could make soldiers invisible to enemies. During the age of Renaissance, Europeans firmly believed that topaz could be used to dispel magic spells. They were also used for the purpose of anger management. In India, it is worn as a part of a necklace to bring health and intelligence to the wearer. Romans considered topaz therapeutic for failing eyesight. They used to put topaz stones on closed eyelids as  treatment.

Uses of Topaz

Topaz with yellowish color display has been used for thousands of years as a gemstone. Few hundred years ago, it was realized that natural topaz can occur in a wide range of colors. As a gemstone, it has several uses.

Birthstone of November Babies

Other than citrine, yellow topaz is also the birthstone of those born in November. Wearing this birthstone is said to have many positive effects on the wearer. It can increase the capacity of the person to accept feelings of affection and reciprocate it.

Used for Positive Crystal Energy

There is an alternative school of thought that believes that crystals can emit energies with their particular effect on human beings. There are many supposed benefits of the crystal energy of topaz. For instance, it can be used to alleviate pains associated with arthritis and rheumatism. It is supposed to improve the functions of the endocrine glands. Topaz energy is also beneficial for eyes; it can ease eye strain, and improve eyesight.

Topaz as an Abrasive Material

Topaz naturally occurs in many shapes, colors and qualities. Lower grade topaz can be used as an abrasive in many industries and products. For instance, it is used in the making of scouring pads and knife sharpeners due to its abrasive qualities.

Treated Topaz Stones

Since colorful topaz stones are very rare in nature, colorless specimens are also subjected to different treatments to bring a desired color shade. They are subjected to heating and coating of metallic oxides on their surface. Different metallic oxides are used to produce different colors. These treated topaz stones are used to make different jewelry items.

Minerals

Geodes – A Natural Pouch of Stunning Minerals

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Geodes are spherical and semi-spherical rock structures that appear like any other rock from the outside, but are different on the inside. They have an internal cavity that is filled with a variety of minerals. The presence of different valuable minerals inside makes them look attractive. Therefore, these rocks are one of the most sought-after geological structures that professionals and collectors alike strive to acquire.

Natural Formation of Geodes

The formation of these special stones sounds like a tale of magic realism. Hollow cavities inside geodes are made when they take the shape of rocks from cooling magma or lava. Cavities are made inside rocks when a bubble of water vapor or carbon dioxide is formed in the flowing lava.

Cavities can also be made underwater when lava cools down to solidify in water. The outside surface of the melted magma solidifies before the inside. The liquid lava trapped inside causes the newly solidified crust of rock to leak. Once all the liquid has leaked out, a hollow space is left inside.

After the cavity is formed inside the geodes, the treatment of mineral-rich groundwater starts. Water accumulates a thin layer of minerals inside the cavities by seeping through porous rocks. It is imperative to mention that the process of mineral accumulation take a lot of time. The buildup of minerals gets transformed into crystals and this can take thousands of years. Some large crystals can take even few million years to grow into their final shape.

Geodes are special and rare geological structures and cannot be found in every rock formation. They are usually found in those areas where rocks are formed in a peculiar geographical environment.

Most geodes deposits are found in:

  • Stratified volcanic deposits of tuffs and basalts
  • Sedimentary carbonate deposits of dolomites and limestone

Small amounts of geodes can be extracted from some other rock formations as well.

Which Minerals Stones are Present in Geodes?

Not all geodes are lined with the same type of mineral residue. However, tiny quartz crystal and agate are mostly found inside geode cavities. But there are geode deposits that are lined with more precious minerals.

Purple amethyst, white calcite crystals, pink rhodochrosite, opals with spectacular play of color and colorful agates are also found inside some rare geodes. Geodes don’t have a definite size. Their size can vary from few centimeters to several meters.

Utilities of Geodes

Until they are unopened, there is no general interest in these stones. However, when they are opened and the inner lining of these stunning minerals becomes visible, then they become the center of attention for many reasons.

Collector-quality Geodes

After determining the quality of minerals present inside, there are some geodes that are sold in auction and with astounding price tags. The price of rare geodes can easily race up to five digits. Affluent people with a hobby of precious stone collection take interest in those collector quality geodes.

Geodes:  Decorative Tools

Large pieces of geodes that are mostly lined with agate and quartz are cut into small blocks and pieces with flat base to produce desk sets, clock faces and paperweights. Geodes used to make those economical products are abundant in nature and contain less striking agate and quartz colors like gray and white. These small geode units are often dyed and polished with vibrant colors to make them more appealing for customers.

Fine grade geodes (rocks lined with amethyst) are cut into different artistic shapes and used with weighted base or stand to be used as items of décor in residential and office spaces.

Beware of Fake Geodes

If you are paying a hefty amount for geodes, then beware. Fake geodes are also available in the collectors market. Highly skilled con artists line actual mineral stones inside pottery structures, which looks very identical to the original geodes.   

Geode Sites in the United States

Lake Superior Agate

Located in the state of Minnesota, this lake is a buildup of agate that fills the cavities of basalt. It has formed in billions of years.  Most of the geodes have eroded mineral linings, however some stones still contain linings of crystalline quartz and agate of orange and red shades due to higher amounts of iron impurities in the lined minerals.

Howard Fensterman Minerals