Agate Gemstone

What is Agate?

Agate is the name given to numerous varieties of banded Chalcedony, a mineral of the Quartz family. Its name comes from the Achetes River in Sicily, where Agates were first found. Usually banded in layers, or stripes, some varieties have "eye" markings, or specks of colour, some have fossilised inclusions, and others are solid. Called the earth rainbow, the concentric bands of Agate form in nearly every colour the earth can produce, including a colourless form.

It is a translucent variety of microcrystalline quartz. It is used as a semiprecious stone when it is of desirable quality and colour. Agate generally forms by the deposition of silica from groundwater in the cavities of igneous rocks. The agate deposits in concentric layers around the walls of the cavity, or in horizontal layers building up from the bottom of the cavity. These structures produce the banded patterns that are characteristic of many agates.

Coyamito Agate.

History

Historically, Agate has been discovered with the artefacts of Neolithic people, and was used as healing amulets and ornamentation dating back to Babylon. Its medicinal uses continued through the ancient Greek and Egyptian civilisations, and spread throughout Africa and the Middle East into Russia. Agate sparked a world renowned stone-cutting and polishing industry in Germany that flourished from the 15th to the 19th century, and exists today.

Petrified wood agate.

Metaphysically, Agate has a lower intensity and vibrates to a slower frequency than other stones, but is highly regarded as a stabilising and strengthening influence. The layered bands of microscopic quartz in Agate may appear delicate, they are actually very strong. Agate is excellent for balancing emotional, physical and intellectual energy, and in harmonising yin and yang, the positive and negative forces of the universe.

Agate occurs in a wide range of colours, which include brown, white, red, Gray, pink, black, and yellow. The colours are caused by impurities and occur as alternating bands within the agate. The different colours were produced as groundwater of different compositions seeped into the cavity. The banding within a cavity is a record of water chemistry change. This banding gives many agates the interesting colours and patterns that make it a popular gemstone.

Agua Nueva agate.

Types of Agates

The world of agates is a fascinating and ever evolving places. There are hundreds, if not thousands of types of agates. They are found around the world. They bring a wonder and magic to the planet with their swirls of colour bands.

Blue Lace Agate, Crazy Lace Agate, Dendritic Agate, Fire Agate, Laguna Agate and Moss Agate.

A matched pair of bookends cut from a large agate nodule.

Agate Gemstone

Agates have been used as gemstones for thousands of years. They were some of the earliest stones fashioned by people. Today they are cut into cabochons, beads, small sculptures, and functional objects such as paperweights and bookends. Agate cabochons are popular and used in rings, earrings, pendants, and other jewellery objects. Agate beads are commonly made into necklaces and earrings. Some have been used as marbles.

Tumbled Agate

Agate is the most popular rough for producing tumbled stones. It is generally inexpensive and can be tumbled with good results by beginners. It has a hardness of seven and can be loaded into a rock tumbler with jasper and any of the quartz varieties.

More About Agate

Most agate has unimpressive colours and patterns. However, agate is a porous material that readily accepts dye. Most of the spectacularly coloured agates sold in the gemstone trade have been dyed. Rarely, the colour patterns of an agate form interesting landscape scenes. These are sought after by collectors.

Moss agate

Moss agate contains green filament-like inclusions, giving it the superficial appearance of moss or blue cheese. There is also tree agate which is similar to moss agate except it is solid white with green filaments whereas moss agate usually has a transparent background, so the "moss" appears in 3D. It is not a true form of agate, as it lacks agate's defining feature of concentric banding.

Agate Healing properties

Metaphysically, Agate has a lower intensity and vibrates to a slower frequency than other stones, but is highly regarded as a stabilizing and strengthening influence. The layered bands of microscopic quartz in Agate may appear delicate, they are actually very strong. Agate is excellent for balancing emotional, physical and intellectual energy, and in harmonizing yin and yang, the positive and negative forces of the universe.

Blue lace agate

Blue Lace Agate has a soft, soothing elegance; like sky-blue waters released from winter's grasp. Its graceful, circular design has a stimulating, positive effect on emotions and attitude. It is not a stone of protection, but rather of encouragement and support. Its circular flowing energy calms, uplifts and elevates.

Crazy lase agate

Crazy Lace Agate is called the Laughter Stone, or "Happy Lace." It is associated with sunny Mexican fiestas and dancing, and brings joy to those who wear it. It is not a stone of protection, but of support and encouragement, elevating thoughts and promoting optimism. Its graceful design, in random lacy patterns, creates a circular flow of energy, stimulating for the mind and attitude.

Dendritic agate

Dendritic Agate is known as the Stone of Plentitude. It brings abundance and fullness to all areas of life, from business to agricultural endeavors. It was associated with the ancient Greek dryads, woodland and tree spirits, and was buried in the fields at the time of sowing to insure a good harvest.

Fire agate

Fire Agate, known as the spiritual flame of absolute perfection, carries a great mystery locked inside its deep brown crystal. You need only touch the stone and fiery embers ignite. Peer into its depths and flames leap within its chambers. Study it closely and it will almost show you its secrets.

Laguna agate

Laguna Agate is the most highly praised banded agate in the world. It is known for its extremely tight banding and vibrant shades of red and scarlet. Laguna Agate is found in an area covering roughly four square miles in a remote mountain range in the state of Chihuahua, Mexico.

Moss agate

Throughout history and all cultures, Moss Agate has been known as the crystal of gardeners and agriculture. It was considered a miraculous healing stone for tribal priests of the past, giving them power to interact with our human organic system, and was used as a talisman to make warriors strong and victorious.

Physical Properties of Agate

Chemical Formula	SiO2
Colour	White, Blue, Red, Green, Yellow, Orange, Brown, Pink, Purple, Gray, Black, Banded, Multicolored
Hardness	7
Crystal System	Hexagonal
Refractive Index	1.54 - 1.55
SG	2.63 - 2.65
Transparency	Translucent
Double Refraction	.009
Luster	Vitreous
Cleavage	Indiscernible
Mineral Class	Quartz (Chalcedony).

Alexandrite gemstone

Alexandrite

Alexandrite is named after the Russian tsar Alexander II (1818-1881), the very first crystals having been discovered in April 1834 in the emerald mines near the Tokovaya River in the Urals. The discovery was made on the day the future tsar came of age. Although alexandrite is a relatively young gemstone, it certainly has a noble history. Since it shows both red and green, the principal colours of old Imperial Russia, it inevitably became the national stone of tsarist Russia.Beautiful alexandrite in top quality, however, is very rare indeed and hardly ever used in modern jewellery. In antique Russian jewellery you may come across it with a little luck, since Russian master jewellers loved this stone. Tiffany’s master gemologist George Frederick Kunz (1856-1932) was also fascinated by alexandrite, and the jeweller’s firm produced some beautiful series of rings and platinum ensembles at the end of the 19th and beginning of the 20th century. Smaller alexandrites were occasionally also used in Victorian jewellery from England.

Forming of Alexandrite

Alexandrite is the rare colour-change variety of the mineral chrysoberyl. Its rarity is a result of its unlikely chemical makeup. Alexandrite can only form when aluminium and beryllium combine with trace elements like iron, titanium and, most importantly, chromium. On rare occasion, vanadium may also be present. The unlikelihood of the rare element chromium being in the right place to combine with aluminium and beryllium under exactly the right conditions to create alexandrite is what makes it so rare and valuable

The magic of changing colours.

The most sensational feature about this stone, however, is its surprising ability to change its colour. Green or bluish-green in daylight, alexandrite turns a soft shade of red, purplish-red or raspberry red in incandescent light. This unique optical characteristic makes it one of the most valuable gemstones of all, especially in fine qualities.

Alexandrite is very scarce: this is due to its chemical composition. It is basically a chrysoberyl, a mineral consisting of colourless or yellow transparent chrysoberyl, chrysoberyl cat’s eye and colour-changing alexandrite (also in cat’s eye varieties). It differs from other chrysoberyls in that it not only contains iron and titanium, but also chromium as a major impurity. And it is this very element which accounts for the spectacular colour change. Rarely, vanadium may also play a part. According to CIBJO nomenclature, only chrysoberyls displaying a distinct change of colour may be termed alexandrite.

Like many other gemstones, alexandrite emerged millions of years ago in a metamorphic environment. But unlike many others, its formation required specific geological conditions. The chemical elements beryllium (a major constituent in chrysoberyl) and chromium (the colouring agent in alexandrite) have contrasting chemical characteristics and do not as a rule occur together, usually being found in contrasting rock types. Not only has Nature brought these contrasting rock types into contact with each other, but a lack of the chemical element silica (the second most common element in the Earth's crust) is also required to prevent the growth of emerald. This geological scenario has occurred only rarely in the Earth's history and, as a result, alexandrite crystals are very scarce indeed.

Alexandrite mining

Russia has remained the primary source of alexandrite since gems from the mines of the Urals became available on the market. When the Russian deposits were thought to have been exhausted, interest in the unique colour miracle decreased - especially since alexandrites from other mines hardly ever displayed the coveted colour change. But the situation changed dramatically in 1987, when alexandrites were discovered in a place called Hematita in Minas Gerais, Brazil. The Brazilian alexandrites showed both a distinctive colour change and good clarity and colour. Thus the somewhat dulled image of the miraculous stone received another boost. The colour of the Brazilian stones is admittedly not as strong a green as that of Russian alexandrite, but the colour change is clearly discernible. Today Hematita is one of the most important deposits of alexandrite in economic terms. Occasionally alexandrite with chatoyancy is discovered there, an effect which has not yet been observed in Russian alexandrite. Alexandrites are also obtained from sources in Sri Lanka, but the hue of these stones compares less than favourably with that of the Uralian alexandrites. They appear green in daylight and a brownish red in artificial light. The Tunduru area in southern Tanzania has also produced some outstanding specimens since the mid-1990s. Alexandrites are also found in India, Burma, Madagascar and Zimbabwe. Although this stone is still considered a rarity, specialised gemstone dealers do stock it, especially since improved trade relationships between Russia and the rest of the world have ensured a better supply of Russian alexandrites to the market.

Physical properties of Alexandrite

Chemical Formula	BeAl2O4
Colour	Blue, Red, Green, Yellow, Pink, Purple, Gray, Multicolored
Hardness	8.5
Crystal System	Orthorhombic
Refractive Index	1.744 - 1.755
SG	3.5 - 3.8
Transparency	Transparent to nearly opaque
Double Refraction	.009
Luster	Vitreous
Cleavage	1,1 ; 3,2. Often exhibits parting along twinned crystals.
Mineral Class	Chrysoberyl