Alexandrite



(color change chrisoberyl)

What makes alexandrite so special? Natural alexandrite is a unique type of chrysoberyl that has color changing properties, from bluish green when viewed in the daylight or in fluorescent light to brownish or purplish red when viewed in the dark lit with an incandescent light from a lamp or candle flame. The finest quality stones will change color from traffic light green to traffic light red. Lab created alexandrite should exhibit the same “emerald by day, ruby by night” effect as its natural cousin. However, I have been unable to find any lab created rough that even comes close to displaying these color changing characteristics.

Chemical Composition - BeAl2O4
Crystal System - Orthorhombic
Hardness - 8.5
Specific Gravity - 3.5 to 3.8
Refractive Index - 1.744 to 1.755
Double Refraction - .009
Cleavage - 1,1 ; 3,2. Often exhibits parting along twinned crystals.
Color - Blue, Red, Green, Yellow, Pink, Purple, Gray, Multicolored.

Where is alexandrite mined? There is virtually no alexandrite coming from Russia these days. Between 1833 and 2008, Alexandrite has been discovered not only in Russia but in Australia, Brazil, India, Madagascar, Myanmar, Sri Lanka, Zimbabwe, Tanzania and the US. This list may seem long, but the production of top quality alexandrite from any of these mines has been relatively small. Currently, the best alexandrite comes from the Hematita mine in Brazil.

Ref: http://www.alexandrite.net/

Today, several labs can produce synthetic lab grown stones with the same chemical and physical properties as and these stones are more difficult to identify. Since synthetic alexandrite share the same chemical and physical properties with natural alexandrite and normal gemological tests for density and refractive index will be of little use and gemologists must use magnification to study the inclusions in order to determine the origin of the material. Synthetic alexandrite may contain curved striations, flux inclusions, triangular metallic platelets, or gas bubbles, depending on the growth technique used.

Flux grown is more difficult to identify because the inclusions of un-dissolved flux can look like natural inclusions. Alexandrite grown by the flux-melt process will contain particles of flux, resembling liquid feathers with a refractive index and specific gravity that echo that of the natural material. Layers of dust-like particles parallel to the seed plate, and strong banding or growth lines may also be apparent. Some stones contain groups of parallel negative crystals. Flux grown alexandrite, are more difficult to spot because the colors are convincing and because they are not clean. These stones are expensive to make and are grown in platinum crucibles. Crystals of platinum may still be evident in the cut stones.

Czochralski or pulled alexandrite is easier to identify because it is so clean. Curved striations visible with magnification are a dead give away. The color change in pulled stones has seen change from blue to red. Although the stones look nice, the colour change doesn´t resemble alexandrite from any deposit. Seiko synthetic alexandrite have a swirled internal structure characteristic of the floating zone method of synthesis. They have tadpole inclusions (with long tails) and spherical bubbles.

The Inamori synthetic alexandrite had a cat´s eye variety, which showed a distinct colour change. The eye was broad and of moderate intensity. Specimens were a dark greyish-green with slightly purple overtones under fluorescent lighting. The eye was slightly greenish-bluish-white and the stones were dull and oily. They appeared to be inclusion-free and under a strong incandescent light in the long direction, asterism could be seen with two rays weaker than the eye. This has not been reported in natural alexandrite. Under magnification, parallel striations could be seen along the length of the cabochon and the striations were undulating rather than straight, again not a feature of natural alexandrite.

Most gemstones described as synthetic alexandrite are actually simulated alexandrite - synthetic corundum laced with vanadium to produce the color change. ... The material shows a characteristic purple-mauve color change which, although attractive, differs from alexandrite because there is never any green.

The jewelry industry officially insists on full disclosure regarding the nature of the gem material being sold and the major producers of synthetic gems actively support these policies. And although synthetic alexandrite is widely used for jewelry, it is predominantly used as a laser. Alexandrite lasers were initially researched and developed by AlliedSignal Corp. The company invested over $100 million in developing alexandrite laser systems and in the growth of high-quality laser material. They were first developed for military and government applications.

Buy lab grown alexandrite online at Geolite.

Buy lab grown alexandrite online at Do Amore.

Average retail prices for alexandrite 2007 - 2008

Faceted (Alexandrite) 0.5 to 1 carat 1 carat plus
Top Red/Green $5,000 to $15,000/ct to $100,000/ct
Medium Red/Green $3,000 to $9,000/ct to 60,000/ct
Slight Red/Green $100 to $2,500/ct to $6,000/ct
Other colors $1,100 to $8,000/ct to $10,000/ct
Cabochon ( Alexandrite) 0.5 to 1 carat 1 carat plus
Strong red/green $500 to $2,500/ct to $30,000/ct
Cabochon (Cat´s Eye) 0.5 to 1 carat 1 carat plus
Strong red/green $1,500 to $5,000 N/A

Alexandrite commands a high price equivalent to or even exceeding the price of gemstones like, sapphires, rubies, emeralds, and diamonds. Alexandrite from Russia would be more valuable if their origin could be verified and if they were of superior quality. Top-quality alexandrite from Russia has sold for as much as $3000 to $10,000 for a one-carat gem. The price of alexandrite has risen in recent years due to high international demand, especially from Japan, but as a gemstone investment, alexandrite is a good choice because of its rarity, durability and distinctive historical significance.

GIA Information About Alexandrite

 

Natural alexandrites



Tanzanian alexandrite        Indian alexandrite        Brazilian alexandrite
Left: Fine color change and exceptional clarity faceted alexandrite (8.66 cts) from the Tunduru deposit, Tanzania Middle: Faceted alexandrite (2.71 cts) with distinctive color change (bluish green to medium red-purple) from Araku, India.  Right:Very strong color change and good clarity fine alexandrite (3.61 cts) from Hematita, Brazil. 

 

 

Tanzanian Alexandrite

The Tunduru area in southern Tanzania is near the Mozambique border and in the early 1990's produced a large quantity of sapphires, spinels and chrysoberyls. All of the easily accessible areas were mined out within a year. Today, mechanized mining is still producing limited quantities of material. Because the mine is in such a remote region, work is difficult. The Tunduru region has produced a variety of outstanding stones. Some of the incredible finds include a large clean top color 40ct+ rough diamond, some spectacular alexandrites, and vanadium colored chrysoberyls. Alexandrite is also found in Madagascar.

Region Ruvuma Region
Province Ruvuma
Locality Tunduru
Latitude -3.3667
Longitude 36.6833
Altitude 4117

Brazilian Alexandrite

The second largest occurrence of alexandrite in Brazil produced deposits of larger alexandrite, although the majority of stones is occluded and translucent rather than transparent. Fine and gem quality larger alexandrite have been mined in miniscule quantity.

Region Southeast Region
Province Minas Gerais
Locality Esmeraldas de Ferros
Latitude -19.3333
Longitude -42.8667
Altitude 2995

Esmeraldas de Ferros is a very rugged and difficult to access area. Mining is under primitive and dangerous conditions. Some of the smaller alexandrite crystals found are of gem quality, with excellent clarity and strong color change. Many of the larger crystals show a regular pattern of cavities that likely represent inclusions that have weathered away. Others crystals appear to have grown across the foliation of the schist, as shown by trains of micaceous inclusions, which create parting planes and increase susceptibility to physical weathering.

_____________________________

Small amounts of alexandrite with distinctive color change and good clarity have been found at Novo Cruzeiro, but current production of chrysoberyl is low.

Region Southeast Region
Province Minas Gerais
Locality Novo Cruzeiro
Latitude -17.4833
Longitude -41.8833
Altitude 2962

The centre of the mining industry is the state of Minas Gerais, named after the large number of gold and precious stone mines discovered in colonial times. Minas Gerais is also Brazil's main producer of mica, beryl, talc, marble, dolomite, graphite, zirconium, bauxite and nickel. Novo Cruzeiro located in one of the poorest areas of Minas Gerais state in the northeastern region, has a population of 35,000, who live mainly in rural areas. This area was industrialized 30 years ago, but transition areas with rural characteristics persist in the peripheral area of its cities.

_____________________________

 

The Hematita mine is known for the finest alexandrite, but today there are very few high quality alexandrites from Hematita on the market. A new owner has taken over the old Hematita mine and no one knows how much more the deposit can produce, but the material presently is high quality. Some dealers say this deposit is already depleted but this is difficult to verify. Small amounts of alexandrite have also been found a bit further north in Minas Gerais at Malacacheta, Teofilo Otoni and Esmeraldas de Ferros.

Region Southeast Region
Province Minas Gerais
Locality Hematita
Latitude -19.5167
Longitude -43.0333
Altitude 3001

In 1987 a major strike of alexandrite was made at Hematita. As soon as news of the find leaked out, three thousand garimpeiros (independent prospectors) descended on the small valley, five hundred feet wide by six hundred fifty feet long, and began to dig. This "Alexandrite-rush" lasted about four months during the spring and summer of 1987. On average, one person a week was shot to death until bloodshed caused the government to issue an order in June 1987 to shut down. The situation had become so violent that the government had trenched a moat around and posted soldiers on the only remaining operating mine. By this time, the area appeared to be mined out. Estimated production from this strike was two hundred and fifty thousand gem carats in the rough (50kgs) according to "Secrets of the Gem Trade: The Connoisseur's Guide to Precious Gemstones" by Richard W. Wise.

_____________________________

Itaitinga mine located near Hematita, 16 km northeast of Belmont. This alluvial deposit produces an average of five kilograms per day, which yields about 250 carats per month of faceted alexandrite. Some exceptional v-shaped twins up to 22 cm in length were recently recovered from Itaitinga mine.

Region Southeast Region
Province Minas Gerais
Locality Itaitinga Mine
Latitude -19.5167
Longitude -43.0333
Altitude 3001

Minas Gerais has long been one of the world's preeminent sources of colored gems, including emerald and alexandrite and there are two important sources of alexandrite in Minas Gerais: Malacacheta and the Antonio Dias-Hematita-Santa Maria de Itabira area. The mechanized mining and sorting operation at Itaitinga Mine employs over 40 workers. An outcrop of alexandrite-bearing rock was recently discovered at Itaitinga, so production may eventually come from the primary deposit as well as alluvial workings.

_____________________________

Alexandrite is mined sporadically in the Malacacheta. Cat's-eye chrysoberyl is readily available at Teofilo Otoni, albeit in very small sizes, mostly under 0.5 ct. Alexandrite is available in smaller sizes. One excellent eye clean with strong color change alexandrite of about 5 cts was shown at the offices of Stone World in Teofilo Otoni.

Region Southeast Region
Province Minas Gerais
Locality Teofilo Otoni
Latitude -17.8500
Longitude -41.5000
Altitude 1256

Teofilo Otoni located between the stony hills and rocky mountains that are so characteristic of the landscape of the state of Minas Gerais, is Brazil's most important commercial center for colored gemstones, where about 55 percent of the country's output is brought to be sold. It is the beating heart of Brazil's colored gem trade, the town where production from hundreds of small mines dotting the region comes to be bought and sold. Driving through the region, it's common to see tunnels cut into the hillsides -- or, more correctly, the telltale white of the waste rock dumped outside the mine. These are all garimpeiro operations, some literally located in people's backyards.

Most famous chrysoberyl deposits, spread throughout the 1,800 hectares of the Faísca and Crisolita Basins. The cat's-eye chrysoberyl is about 30 percent of the rough found , although only 10 percent of that is good color. Few years ago, Brazil's environmental agency (IBAMA) shut down the Duarte & Bastos's mine for polluting the local stream and deforesting the region, which can cause serious erosion problems. Now, with only a dozen or so miners left, they're allowed to mine on a limited basis while they implement a 20-year plan to replenish the vegetation and build dams to remove soil sediment from the water.

 

Now let me blow your mind!
Try to wrap your head around this.



At the equator the earth spins at 1000 miles per hour = 1609 kilometers per hour.





The earth rotates around the sun at about 67,000 miles per hour = 107,826 kilometers per hour.





The sun is rotating around the galaxy at about 559,000 miles per hour (250 km/s according to Vera Rubin, the lady who discovered this in the 1970's). In fact, the majority of the suns in all galaxies rotate around their respective black hole very close to this same speed. One would expect the rotation to be much like our solar system where the outer planets rotate slower and the inner planets rotate faster. Not so for the stars in a galaxy. Stars, at many varying distances from the black hole at the galaxy center, are all rotating at the same speed. This results in the pinwheel shapes common to most galaxies. No one really knows exactly why this is. It is being explained as the result of dark matter.

Our galaxy, along with the local group of galaxies, is moving through space at about 1,340,000 miles per hour = 2,156,521 kilometers per hour.

Astronomers speculate that space is expanding at about 152,112 miles per hour = 244,801 kilometers per hour.

Add it all up and we are traveling through space at more than 2,000,000 miles per hour = 3,218,688 kilometers per hour. Other estimates say upwards of 2.8 million miles per hour = 4.5 million kilometers per hour. That is somewhere between 550 and 800 miles per second = 1,288 kilometers per second. At that speed you could travel from the earth to the moon, 238,900 miles away, in under 6 minutes. In any case, it is fast - damn fast.

It's hard to imagine traveling that fast. It's impossible to relate to these speeds especially when we feel like we are standing still in space.

As a comparison, the speed of light is 6.706e+8 mph or 670,600,000 miles per hour which is about 671 million miles per hour or about 186,000 miles per second ~ 300,000 kilometers per second.


That is about 300 times faster than we are traveling through space.


Something I should also mention is that in addition to moving through space at such an extreme speed, our sun with the planets moves up and down through the plane of our galaxy like a merry go round while traveling around the galaxy. This merry go round up and down oscillation is on a 60,000 year cycle. So, this up and down movement through the plane of the Milky Way Galaxy takes us into areas of our galaxy that may be less desirable than others. It could take us through debris clouds or near magnetars or black holes that could cause havoc in various catastrophic ways for the earth.



Did you know?
- the universe has more platinum atoms than silver atoms? Platinum is the pricier metal because on earth it is much rarer than silver because billions of years ago much of the platinum and gold sank out of the earth's crust and into its core. There is an estimated 6 times more platinum than gold in the earth's core.




Why Is Earth's Weather Changing?

Now let's look at the Earth's path through space and how it affects the weather. Global warming or cooling - absolutely. Manmade - a little but nothing like earth itself. No doubt humankind is contributing to weather change, but the earth's orbit will override and exceed anything man will do.

Why you ask?

The Earth's rotational axis is tilted slightly at 23.5 degrees. The Earth's axis rotates around this circle once every 20,000 years. The north star today is Polaris, however, 5 thousand years ago it was a different star altogether (Theban) and thousands of years from now it will be Vega. Today the orientation is the northern hemisphere is leaning away from the sun. This position is why the Sarah Desert is a desert where it was more tropical, wet, and green 15,000 years ago.



The Earth's orbit around the sun is also not constant and varies widely over time. Today the Earth's orbit around the sum is almost circular so summers and winters are mild. However, due to influences from the Sun and moon, Earth's orbit can go slightly elliptical. The cycle between elliptical and circular is 100,000 years. The effect of this orbital change will be hotter summers and colder winters.


Jupiter and Mars have an even bigger effect on Earth's orbit where a 405,000 year cycle takes the Earth's orbit on an extremely elliptical orbit. This orbit is thought to have been responsible for snowball earth several times in Earth's past.

Yes, Earth's climate is changing, and it is going to change way more dramatically than any of us can imagine. All these orbital changes have happened several times in the past and will happen again many more times in the future. 20,000 years from now there will be vast changes where the Sarah Desert will be green again. But these changes will be the result of the Earth's orbit around the Sun and will probably have little to do with human evolution.

Another event not often associated with weather disturbances is the occasional flip of earth's magnetic field known as geomagnetic reversal. Earth's magnetic poles are not static. The magnetic poles wander and occasionally reverse around every 200,000 to 300,000 years. The Earth's magnetic field has reversed nine times during the past four million years. The last known complete 180-degree magnetic pole shift last happened 42,000 years ago and took approximately 1000 years to complete the shift. As of late, Earth's magnetic North pole has wandered considerably on a path toward northern Russia. Scientists know that Earth's magnetic field has weakened about 9% in the past 170 years. The magnetic North pole has also been drifting more rapidly since the 1990s, at a rate of 30 to 40 miles per year.

The pole shift 42,000 years ago is suspected to have contributed to the demise of Neanderthals. While the poles were shifting, additional cosmic rays and high-energy particles from outer space would have depleted ozone concentrations, opening the floodgates for more ultraviolet radiation in the atmosphere over a long period of time. Shifting weather would have expanded the ice sheet over North America and dried out Australia, prompting the extinction of many large mammal species. Solar storms, meanwhile, might have driven ancient humans to seek shelter in caves. As competition for resources grew, our closest extinct human relative, Neanderthals, may have died out.



But there is more to our travels through space than drastic changes in the weather.

Mass extinctions of life on Earth appear to also follow regular patterns based on our solar system traveling up and down in relation to the galactic plane.

Widespread die-offs of land-dwelling animals which include amphibians, reptiles, mammals, and birds follow a cycle of about 27 million years.

Additionally, these mass extinctions coincide with major asteroid impacts and devastating volcanic outpourings of lava, rock, and a lethal amounts of deadly gases poisoning the atmosphere.

Global mass extinctions are presumably caused by the largest cataclysmic impacts and massive volcanism, perhaps sometimes working in concert.

Paleontologists had previously discovered that similar mass extinctions of marine life, in which up to 90% of species disappeared, were not random events, but seemed to come in a 26 million year cycle.

These new findings of coinciding, sudden mass extinctions on land and in the oceans, and of the common 26 to 27 million year cycle, lend credence to the idea of periodic global catastrophic events as the triggers for the extinctions.

Three of the mass annihilations of species on land and in the sea are already known to have occurred at the same times as the three largest impacts of the last 250 million years, each capable of causing a global disaster and resulting mass extinctions.

These impacts can create conditions that would stress and potentially kill off land and marine life, including widespread dark and cold, wildfires, acid rain and ozone depletion. The most infamous asteroid strike we know of is the one that killed off the dinosaurs some 66 million years ago, which overall wiped out 70% of the species on Earth.

It seems that large-body impacts and the pulses of internal Earth activity that create flood-basalt volcanism may be marching to the same 27 million year drumbeat as the extinctions, more than likely paced by our orbit in the galaxy.

And as for where we are in the current cycle, we are about 20 million years away from the next predicted mass extinction that's due to a comet strike or volcanic activity.

How could this be? Aren't asteroid or comet impacts completely random? Not so. Because our sun with the planets travels up and down through the plane of our galaxy like a merry go round while traveling around the galaxy, our planet will pass through a crowded part of our Milky Way galaxy about every 30 million years. During those times, comet and meteor showers are more likely, leading to large impacts on the Earth.

The above study was published 12/11/2020 in the journal Historical Biology.

 

BUT WAIT - THERE'S MORE

Mark has had a theory for a very long time. We know from Albert Einstein that time and space are relative and therefore are not constant. Affecting one affects and changes the other. Gravity warps space and also time. Speed also warps time. Time runs slower wherever gravity is strongest. This is because gravity curves space-time. Also, the faster the relative velocity between two people or places, the greater the time dilation between one another. They say this rate of time diminishes to zero as one approaches the speed of light. This effect is not linear. It is exponential like the Mohs hardness scale or the Richter earthquake scale. For sufficiently high speeds, near the speed of light, this effect is dramatic. For example, a persons perceived one year of travel near the speed of light might correspond to ten years of time on Earth. That said, our time here on earth is influenced by speed because, as you know, we are traveling through space at somewhere around 2+ million miles per hour. So we can see that our perceived time is slower, about 0.5% slower, than the time of something standing still in space. We also know on earth we are influenced by the gravity of the earth, the sun, and the galaxy we are traveling through space in so our perceived time is also slowed by all that gravitational influence. This effect is also exponential where higher gravitational influence cause the most dramatic effects. Adding up the slowing of our time resulting from our speed and the gravity that is influencing us means that our perceived time is slower than actual time in space without these influences. So, when we look out into the universe, we see the universe not only expanding but speeding up (accelerating) because our time is running slower than what we are looking at. Therefore, Mark doubts that the speed of galaxies in the universe are accelerating away from one another as scientist's have speculated. The universe is expanding, maybe, but not accelerating. Mark has been mulling over this concept for years. Some think this concept has merit and many think it is nuts. What do you think?

Today's theories speculate that the galaxies in the universe are all speeding away from one another as a function of their distance apart where some galaxies are traveling away from us at more than the speed of light because space in that area is expanding at greater speeds the farther something is away. So, a galaxy 4 light years away is traveling away from us 4 times faster than a galaxy 2 light years away. If we were to travel at the speed of light in one direction, there would be galaxies disappearing before our eyes because they are so far away that they are moving away from us faster than the speed of light because where they are space is expanding faster than the speed of light. Furthermore, this expansion of space in all directions is going on relative to every other point in space. This is supposedly all caused by a substance we can neither see and apparently does not affect us - dark matter and dark energy. Called dark because we have no idea what it is but without it the universe does not work.

Moving on - they say the H0liCOW estimate puts the Hubble constant at about 71.9 kilometers (44.7 miles) per second per megaparsec (one megaparsec equals about 3.3 million light-years). In 2001, Dr. Wendy Freedman determined space to expand at 72 kilometers per second per megaparsec - roughly 3.3 million light years - meaning that for every 3.3 million light years further away from the earth you are, the matter where you are, is moving away from earth 72 kilometers a second faster. In 2015, another team, using observations of the cosmic microwave background, determined the rate was 67.8 kilometers per second per megaparsec. Time dilation in a gravitational field is equal to time dilation in far space, due to a speed that is needed to escape that gravitational field.
Here is the proof:

Dilation equation