aquamarine | Rock & Gem Magazine https://www.rockngem.com Rock & Gem Magazine Mon, 02 Oct 2023 13:24:51 +0000 en-US hourly 1 https://wordpress.org/?v=6.3.2 https://www.rockngem.com/wp-content/uploads/2018/10/cropped-Favicon-32x32.jpg aquamarine | Rock & Gem Magazine https://www.rockngem.com 32 32 What are the Birthstones by Month? https://www.rockngem.com/birthstones-stick-with-the-standards-or-choose-your-own/ Mon, 02 Oct 2023 10:00:42 +0000 http://www.rockngem.com/?p=7495 What are the birthstones by month? What is your birthstone? For as long as humans have been fascinated with precious gems, they have assigned special significance to them. The 12 zodiac gems formed the basis of the modern, Western birthstone list. The Jewelers of America established a list of birthstones in 1912 that remains the […]

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What are the birthstones by month? What is your birthstone? For as long as humans have been fascinated with precious gems, they have assigned special significance to them. The 12 zodiac gems formed the basis of the modern, Western birthstone list. The Jewelers of America established a list of birthstones in 1912 that remains the standard today. Alternative lists also exist and who’s to say you can’t choose your own?

January

gemstones-by-month
Garnet

Garnet has been the birthstone for January since the 15th century, at least. With a Mohs hardness of 6.5 to 7.5, it can be faceted into beautiful gemstones that wear well in jewelry. Since the term “garnet” actually refers to a group of nesosilicate gems, those born in this month can choose from a rainbow of colors.

The most common members are red almandine, an iron-aluminum silicate; red pyrope, a magnesium aluminum silicate; orange-yellow spessartine, a manganese aluminum silicate; the yellow or green varieties of andradite, a calcium-iron silicate; predominately green grossular, a calcium-aluminum silicate; and rare, bright-green uvarovite, a calcium chromium silicate.

February

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From the 15th century to the present, amethyst has been the preferred birthstone for February. Amethyst belongs to a mineral family that can compete with garnet for diversity of color: quartz.

Pure quartz is colorless, as exemplified by Herkimer diamonds. The causes of amethyst’s shades of pale violet to rich purple are radiation and the inclusion of iron impurities and trace elements.

As a rule, amethyst crystals are short and stubby, and occur in large numbers, often filling a large vug a hollow petrified tree section, or lining the inside of a geode. Fine crystals that are large enough to produce a faceted gem of over 20 carats are rare.

March

gemstones-by-month
Aquamarine

The current choice of a birthstone for March is aquamarine. Aquamarine is a variety of beryl (Mohs 7.5-8). Its name was derived from the fact that the beautiful, transparent, blue-green coloration of the gem resembles that of seawater. It can be found in translucent to transparent crystals that form in the hexagonal system. The six-sided crystals are often striated lengthwise.

Aquamarine develops in metamorphic rocks and, more often, in pegmatites.

April

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Diamond

Before 1900, a person with an April birthday had two choices of birthstone: diamond or sapphire. During the 20th century, however, diamonds became the preferred stone.

Diamond, a mineral consisting of pure carbon, heads the list of all gemstones for its beauty and hardness. A 10 on the Mohs Scale of Hardness, it is resistant to scratching and is an ideal gem to set in rings. Its hardness results from the arrangement of its atoms in cubes.

All diamonds have slightly rounded faces, and they’re so smooth they feel greasy to the touch. They can be colorless and water clear to blue, pink, yellow, brown, green or black, and transparent or translucent. They shine with an adamantine luster when held to the light.

May

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Emerald

There were two choices for May birthstones for several hundred years: emerald and agate. The popularity of agate seems to have waned at the turn of the 20th century, so emerald is now the favorite. It’s the green member of the beryl family of gemstones. The color varies from bright green to pale green and, sometimes, darker shades of blue-green.

Fine emeralds have a velvety surface appearance and, in the better stones, an even distribution of color. One bad trait of emeralds is a tendency to have inclusions. It’s rare to find an emerald without some slight imperfection. This in no way deters from the beauty of this gemstone, though. It can also be one way of determining whether an emerald is a simulated gem or the real thing, as manmade stones have no imperfections.

June

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Pearl

The contemporary choices for June are pearl, moonstone and alexandrite. Of course, a pearl is the organic product of marine bivalves and not a mineral.

Moonstone is a variety of feldspar that shows adularescence, or schiller, an optical effect that produces a milky luster with a bluish tinge that appears to move across the stone when it is tilted. The phenomenon is named after the feldspar variety adularia.

Alexandrite is a color-change variety of chrysoberyl (beryllium aluminum oxide). This is a very rare and expensive gemstone. It has a hardness of 8.5, and its crystals are either tabular or prismatic. The distinction between alexandrite and chrysoberyl is simply color. A strange characteristic of alexandrite is that it is red, purple or violet when held under artificial light, but in daylight, it looks green.

July

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Ruby

Ruby is the standard birthstone for the month of July. It is a corundum (aluminum oxide) gem that gets its color from the presence of chromium in its structure. An exceptionally hard mineral, corundum illustrates a hardness of nine on the Mohs scale. “Pigeon-blood” red is the preferred color for rubies, though they also occur in lighter shades, including pink. All other colors of corundum are called sapphires.

Ruby exhibits all the desirable properties of a jewelry stone: beauty, durability, optical properties, and rarity. Some rubies display a star or asterism when fashioned into a cabochon. This effect is caused by the reflection of light from numerous inclusions of minute, needle-like crystals of rutile. Corundum crystallizes in the hexagonal system with a tabular-barrel-shaped habit.

August

gemstones-by-month
Peridot

Current birthstones for August are peridot, the gem-quality form of olivine and spinel. Olivine makes up a large portion of the earth’s mantle. Rocks containing olivine have been brought to the surface by volcanic action and actually blown out in the form of volcanic bombs. Masses of olivine have been found in meteorites, and the Apollo astronauts brought basaltic rocks back from the moon that contained olivine.

A popular jewelry stone, peridot has a hardness of 6.5-7 and can be transparent or translucent, with a vitreous luster. Its color shades from deep green to apple green, yellow-green or olive. It’s most often found in granular nodules, forming short, prismatic crystals in the orthorhombic system.

Spinel is the gem-quality member of the larger spinel group. Its hardness (Mohs 7.5-8.0) makes it ideal for jewelry use. Its spectrum of colors includes red, pink, purple, blue and lavender. In times past, red spinel was often mistaken for ruby. A notable example is the Black Prince’s Ruby, set in the royal crown of England.

September

gemstones-by-month
Sapphire

The birthstone for September is sapphire. This term refers to any corundum (aluminum oxide) gem that has any color other than red (ruby). Sapphires may be colorless, blue, green, yellow, orange, brown, pink, purple, gray, black, or multicolor. At Mohs 9, its hardness is second only to that of a diamond.

Heat treatment is sometimes used to give natural blue sapphires a deeper, more pleasing color. Natural star sapphires, which display the optical phenomenon of asterism, are very rare.

October

gemstones-by-month
Opal

Two options for October are opal and tourmaline. Opal is a magnificent gemstone with a play of color or “fire” in all colors of the spectrum. Spaces between the tiny spherules of silica that make up the gem diffract light into its spectral colors. Red, yellow, green and blue, in strong to pastel shades, flash from the stone when it is tilted.

Opal occurs in common and precious types. Common opal does not display any reflective fire. It may have a honey-yellow, brown, gray or colorless body color that is milky and opaque. Opal (Mohs 5-6) is not a very hard gemstone.

Tourmaline, a silicate of boron, has a complicated chemical composition, in which a number of elements, including calcium, iron, sodium and aluminum, may combine. It has a Mohs hardness of 7-7.5.

It belongs to the trigonal crystal system and its habit is hemimorphic (a crystal having two ends of an axes unlike in its planes).

Because of the coloration of the individual stones, tourmaline has several names, including schorl (black), rubellite (red), indicolite (blue), and dravite (brown). Tricolor crystals are common. The popular watermelon variety has an outer layer of green around a red core.

November

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Topaz

The current birthstones for November are topaz and citrine. People tend to think of topaz, a silicate mineral with aluminum and fluorine, as a yellow stone, but heat-treating and color-enhancing adaptations have made blue the predominant color on the market. It is an allochromatic mineral, which means its color is caused by internal defects in the crystal and has a Mohs hardness of eight.

Citrine is the golden member of the quartz family (silicon dioxide). Though quartz in its many forms is one of the most abundant minerals on earth, fine, gem-grade crystals are not that common. Citrine is affordable and, when faceted, rivals more expensive gemstones in beauty.

December

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Turquoise

There are three birthstones for December: turquoise, blue zircon and tanzanite. Turquoise (hydrated copper aluminum phosphate) is an opaque, blue-to-green, massive gem material. It has a relatively low hardness of Mohs 5-6, so care must be taken with turquoise jewelry.

The rarest and most valuable variety is robin’s-egg blue with black “spiderweb” veins of limonite. Fake turquoise, consisting of dyed howlite or magnesite, is common. Buyer beware.

Zircon (zirconium silicate) can be blue, black, red, brown, green, yellow, smoky, or water-clear. It has an adamantine luster much like that of a diamond, and it is often misidentified as such.

Tanzanite, the blue/purple variety of zoisite (basic calcium aluminum silicate), is a recently introduced alternative for December. Tanzanite crystals in shades of yellow to brown, green, pink, gray or blue are often heat-treated to produce a gemstone that is a beautiful and permanent blue.

This story about what are birthstones by month previously appeared in Rock & Gem magazine. Click here to subscribe! Story by Kenneth H. Rohn.

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Topaz & Diamond Hunting in Australia https://www.rockngem.com/on-the-hunt-for-topaz-and-diamonds/ Mon, 21 Aug 2023 10:00:13 +0000 https://www.rockngem.com/?p=10744 Family trips hunting for topaz and diamonds in Australia by the dinner plate full leads to a lifetime passion for rockhounding. Having caught the gemstone-hunting bug early in my life chasing sapphires at the Anakie gem fields (Central Queensland, Australia in the early 1970s), I have always loved the thrill of the hunt for shiny […]

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Family trips hunting for topaz and diamonds in Australia by the dinner plate full leads to a lifetime passion for rockhounding.

Having caught the gemstone-hunting bug early in my life chasing sapphires at the Anakie gem fields (Central Queensland, Australia in the early 1970s), I have always loved the thrill of the hunt for shiny things. They don’t have to be valuable shiny things, just a tiny piece of God’s creation that nobody had ever seen before I laid my hand on it.

Learning Specking

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As kids, we weren’t much into the hard yakka (labor) of digging and sieving, but soon learned the fine art of ‘specking’, which is walking around with eyes glued to the ground in front of us, picking up the bits left behind by more ambitious, or perhaps more discerning, fossickers (searcher for rocks and minerals).

A few of these finds were jewelry-quality though most were not, but that didn’t devalue them in our eyes or make the process of looking for them any less enjoyable. Dirt, sunshine, and freedom to explore the pristine bushland that we camped in with no amenities whatsoever, but when you are a ten-year-old, who needs showers?

Family Move Leads to More Gem Locations

The family moved to Cairns when I started secondary school, and it took us a few years to discover that there were gemstones to be found in North Queensland also, and where they could be lawfully found.

We started making family trips to the Mt. Gibson topaz fields in the early 1980s, by which time I had found a good man to marry, and he caught the gem-hunting bug on his very first trip despite none of us having much idea of what we were looking for.

We had a couple of elderly long-wheelbase Land Rovers that carried us and all the camping gear. The vehicles steadfastly chugged their way up the mountain, albeit with no air-conditioning and springs (shocks) that were built for durability, not for comfort. That was all we needed for a promising long weekend!

Fast forward some 30 years, and in the company of our adult children and their significant others, we were still eager to find more lovely topaz and headed to another fossicking area called O’Brien’s Creek, 37km (22 miles) north of Mt. Surprise and just over 400km (248 miles) from Cairns.

Surface fossicking will yield lovely smoky quartz crystals as well as topaz and aquamarine.

The Atherton Tablelands

After leaving tropical Cairns on the coast, two routes lead to the Atherton Tablelands. This area is known for beef/dairy farms and fields of sugarcane, maize, potatoes, peanuts, fruit, and vegetables of all kinds.

Travelers are advised to follow the signs that point toward Herberton/Ravenshoe and enjoy the sight of the majestic wind turbine farm and the dairying district of Ravenshoe. A must-remember destination on the path to the dig site on the return trip is the hot thermal springs at Innot Hot Springs – heavenly for a good long soak after a day’s digging.

The route takes travelers through the tin mining area of Mt. Garnet. This distance of 192km (119 miles) takes about 2.5 hours to travel from Cairns. The next leg of the journey involves another 62km (38 miles) southwards through the quaint town of Mt. Garnet, along the Kennedy Development Road through the 40-Mile Scrub with its unusual Queensland Bottle Trees. Then it’s westward to Mt. Surprise township. This road is all-weather bitumen (asphalt) and the journey takes travelers another 73km (45 miles). The final turn off the main highway brings rockhounds toward the O’Brien’s Creek fossicking area, which is well-identified at the western end of the town, just opposite the local police station.

Accommodations

The town of Mt. Surprise has several motels and good caravan parks. However, the O’Brien’s Creek camping area (which is situated squarely on the banks of Elisabeth Creek) with its hot showers and toilets, and large campsites on the banks of the beautiful creek abounding with birdlife, is undoubtedly a choice location. Camping is not permitted within the boundaries of the designated fossicking area.

Waterworn ‘pigeon eggs’ found on an O’Brien’s Creek hilltop were carried there by ancient paleochannels.

The camp area is amazingly pleasant, with Elizabeth Creek flowing most of the year, an unusual occurrence in the harsh environment of this country. During school holidays, families set up camp, relax and paddle canoes along the creek.

Twitchers (birdwatchers) and wildlife enthusiasts make the journey to camp here specifically to watch the apostle birds, bower birds, and blue-aced honey-eaters. They make themselves at home around your campsite, with kookaburras and butcherbirds waiting for, or stealing, a snack from unguarded plates. Mother galahs feed their babies while crimson-wing and rosella parrots feed on grass seeds almost at your feet. Big flocks of black cockatoos land for a late afternoon drink on the sandy river banks.

Digging for Topaz

Gem-quality stones were plentiful and were measured by the dinner plate full in the early days of the fossicking field, but constant picking over has reduced the finds considerably. This area was extensively mined for tin in the late 1800s, using only hand tools, with little mechanical assistance and often little or no water.

These dedicated miners found tin, but they saw no value in the shiny chunks of topaz they turned over in the process, so they left them behind in the tailings and mullock heaps. These are what fossickers chase today. There are still active mining leases in the area, of which few are worked consistently, but they remain out of bounds to fossickers.

If you are traveling in a conventional vehicle, fields of the Designated Fossicking Area (DFA) signposted ‘Tourmaline Gully’ and ‘Crystal Gully’ are generally easily accessed and the first places to visit. The access road runs along the western side of O’Brien’s Creek, and numerous tracks are leading into the sandy creek beds where fossickers have been at work.

Dry sieving in the creek can produce lovely topaz, quartz crystals, tin crystals (cassiterite), and the rarer aquamarine, especially after the wet-season rain scours the creek banks. Rockhounds do have to expend considerable effort removing large rocks, tree roots, and other obstacles to process new ground.

Geology Contributes to Rock Shape

Examples of gemstones found during 2017 at O’Brien’s Creek. Left to right, Pigeon eggs, tin crystal, rough and cut garnets (not all local), rough and cut smoky quartz, aquamarine, and rough and cut topaz.

These finds are generally more waterworn and rounded than stones found in the higher areas, which are sharper-edged and more crystalline in appearance. Evidence of digging in the river bank is visible everywhere, so visitors are advised to choose an appealing place and heft the shovel. As the DFA is part of a working cattle station, fossickers need to be aware of wandering stock, and the fertilizer they leave in their wake.

Since 1968, the Australian Government has set aside ‘Designated Fossicking Areas’ throughout Australia that permit people to fossick for gemstones and gold. Most of these areas are on private land, and landholders allow people to hunt gems in these areas providing they do not interfere with farming activities. A fossickers license is required in Queensland whether the fossicker is using private land or digging in a designated fossicking area. These licenses can be bought online at the ‘Department of Natural Resources, Mines and Energy’ for around $75 AU (around $50 U.S.) for a year.

Visitors to the area will see the proof of many eager people having worked the top of the hill. This area produces lovely smoky quartz crystals, and the locals swear they have found
tourmaline here also.

If you have a 4WD and are not afraid to get it slightly battered, then the Blue Hills and McDonald Creek fields are the place to go. Being less accessible, not so much fossicking activity has taken place here as in other sites. The road was initially built for use by tin miners and kept in good condition. However, once
the tin mining declined, the constant use, no maintenance, and numerous wet seasons have made the road pretty rough – especially on the two jump-ups (short, steep rises).

These fields are where quality blue topaz can be found in the dry creek beds and by digging at the top of hills. Topaz crystals are also collected along the track toward the Six-Mile Creek area. Just walking over the ground that looks undisturbed is worthwhile for specking glints of topaz sitting on the soil surface, exposed by the elements.

The locals advise that moving a boulder and digging a little on the uphill side may bag you a gem, as topaz is weightier than the average creek gravel and tends to get lodged in back-wash crevices during flood events. A member of our family found a perfect aquamarine crystal here. It was sitting on the surface of the soil, catching her eye This crystal was since valued at between $1,200 and $1,800 as a rough specimen, all in a good day’s work!

The Difference Between Topaz & Diamonds

I mentioned to a Cairns geologist with whom I had previously worked that I was going fossicking at O’Brien’s Creek. He said, “Keep your eyes open for diamonds while you are there.” I asked, “How would you tell the difference between a diamond and a topaz?” His reply was, “You will certainly know the difference when you see it.”

That conversation reminded me of an incident that occurred when I worked as a GIS Officer (mapping) for an exploration company in Ravenshoe, North Queensland. A ‘tin scratcher’ came to the office to ask the geologists if a stone he had found might be a diamond?

Of course, everyone’s eyes lit up as we all gathered around the weather-beaten hand that held the find. Yes, though small, it was confirmed to be a diamond. The was suitably vague about where he had found it and replied, “out near Mt. Surprise.” That was in the late 1980s, and his words remained in the back of my mind since.

In 2016, while researching the history of tin miners who worked along Elizabeth and O’Brien’s Creeks, and Angor, a tin mining shantytown of the 1880s in the Mt. Surprise area, I came across a public company report that summarized all previous reports written for this region. It immediately caught my interest, and I admit to doing a little chicken dance around my office when the summary included reports of companies specifically looking for diamonds. The summary report was written in December 1993 by a consulting geologist for Northern Diamonds Pty Ltd. His report stated that up until 1993, 53 diamonds had been reportedly found in colors ranging from white to yellow. The sizes ranged from 0.3 carats to 5 carats, the latter being the largest noted.

Finding a male Great Bower Bird’s tunnel can be a treasure trove in itself as they collect pretty stones to decorate the nest and attract a mate.

During the 1980s, another geologist had contacted the people who had found the first 26 diamonds. He sent some of these to South Africa to be tested to determine their quality. The results were that they were certainly diamonds but not of top gem quality.

This was enough encouragement for exploration companies to continue to search the area of Elizabeth and O’Brien’s creeks until the late 1990s. Currently, diamond exploration is still relatively active in northern Queensland, especially in the Cape York goldfields region.

Discussing Origins of Diamonds

I questioned each geologist or miner I have spoken to about the area about where they thought the diamonds originate.

Confusingly, each geologist has a slightly different theory. The Cairns geologist said the Elizabeth Creek diamonds were formed as far away as the Palmer River in the Cape York area and migrated along the waterways. The consulting geologist who wrote the 1993 report speculated that they were local and traveled the Red River lineament. He stated that in his opinion, all the diamonds found up to that date ‘were associated with a 50km long relict Cretaceous placer, which parallels Elizabeth Creek’. He goes on to say, ‘The placer is characterized by well-rounded quartz pebbles known locally as ‘pigeon egg wash.’ We did find some of these ‘pigeon eggs’ on the top of a hill in the fossicking area, which may have journeyed along ancient paleochannels (riverbeds), and this speaks of significant geological upheaval activity.

Rusted relics from the former tin mining era. Gemstones are not the only treasures found in this field.

The areas of Elizabeth and O’Brien’s Creeks are identified as being one of several relict Cretaceous mineralized river systems. The systems contain cassiterite, ilmenite, zircon, monazite, garnet, and gold. The Elizabeth Creek system is the only one to date known to potentially contain diamonds. Early mining reports reveal that before the1930’s, this area produced 376 tons of cassiterite from alluvium in creeks and gullies, and mining remained spasmodic until 1985 when the price of tin crashed.

The Elizabeth Creek system occurs as a semi-discontinuous group of sand ridges north of and parallels to the present Elizabeth Creek. The major alluvial workings in the area have been for cassiterite in the streams draining the sand ridges over its entire exposed length. The extensive basalt flows from the Undarra Cone to the east have touched this area on its southern boundary.

A word of warning here before venturing on a diamond-only search. Since 1976, only 53 diamonds have been reported as being found, though it is likely that some were not reported, or not immediately identified as being diamonds. The majority were sourced west of the fossicking area, but some came from O’Brien’s Creek within the DFA.

The diamonds in the fossicking area were found in the river bed of O’Brien’s Creek by tin miners and local people living in the area, who honestly believe there is the potential for more to be found. One local who has a Mineral Lease (ML) just outside the DFA, said that he found a diamond while working for a tin mining company in the 1980s.

Each trip to O’Brien’s Creek sees us bring home loads of unknown stones in the event they may be diamonds, as finding one, according to the locals, is entirely possible.

Most of our ‘treasures’ turn out to be chuckers (chuck them away) or leaverites (leave them right there), but it always surprises us when we wash these stones, and a considerable amount proves to be lovely topaz, sometimes blue. On the last trip, along with our aquamarine crystal, we found a small aquamarine chip by specking.

As our research suggests, diamonds have been found in ‘them thar hills’ and your chance of finding one is as good as the next person’s. As an added incentive for the relic-hunting readers, I found some R. Bell & Co match tins in the ruins of a tin mining camp in this area.

The harsh, hot climate makes short work of the temporary, low-cost living quarters the mining camps provided back in the mining heyday. Finding such a site, searching, and waving a metal detector proves there are interesting treasures to be found in the most unexpected places, and it is sad to see little bits of our history is being lost to the elements.

This story about hunting for Topaz and Diamonds appeared in a previous issue of Rock & Gem magazineClick here to subscribe! Story and Photos by Jenni Clark & Leigh Twine.

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A Field Guide to Beryl https://www.rockngem.com/beryl-field-guide/ Mon, 23 Jan 2023 11:00:39 +0000 https://www.rockngem.com/?p=18679 Beryl is a single mineral species that is colorless in its pure form. Impurities give it its color. While beryl is famous as a gemstone, it is a commercially valuable mineral because it is composed of beryllium aluminum silicate. The ancient Greeks used the term beryllos to describe the mineral beryl. It is also a […]

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Beryl is a single mineral species that is colorless in its pure form. Impurities give it its color. While beryl is famous as a gemstone, it is a commercially valuable mineral because it is composed of beryllium aluminum silicate. The ancient Greeks used the term beryllos to describe the mineral beryl. It is also a girl’s name, of Greek origin, which means “sea-green jewel.”

About Beryl

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With a Mohs hardness of eight and several color variations, it is a valuable jewelry gemstone. Color is the most important physical quality of beryl. Emerald (green), aquamarine (blue), heliodor (yellow) and morganite (pink) are the most sought-after beryl gems. Red beryl (bixbite) is very rare and commands a premium price when gem quality. Bixbite has only been found in two locations in Utah. The beryl family contains one of only four gemstones considered to be precious; emerald.

Beryl crystallizes in the hexagonal system often forming large six-sided crystals that are favorites with collectors. It has been found as a “mega” crystal at several localities with the record being one found in Madagascar that was 54 feet long, eight feet in diameter and weighed 400 tons.

The rock types where beryl is most commonly found are pegmatite, gneiss and mica schist.

Famous Emerald

Emeralds are one of the oldest-known minerals. They have been found in tombs in Egypt. According to John Farndon, the oldest Egyptian emerald mines, some 3,500 years old, were discovered by the French adventurer Caillaud in 1816. It is said that the Roman emperor Nero watched through an emerald as gladiators fought.

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Emerald

Beryl Uses

Common beryl (non-gem) is mined as the major source of beryllium used in industry. Beryllium alloys are used in aircraft, missiles, satellites and spacecraft.

Where to Find Beryl

Beryl is mined in the United States (the major producer), South Africa, Zimbabwe, Brazil, Mozambique, Tanzania, Colombia, Afghanistan, Sri Lanka, Madagascar, Zambia, India, Pakistan, Namibia, Nigeria and China.

Youthful Beryl

Beryl is said to have metaphysical properties that include promoting youthfulness, happiness, a balanced nervous system and protection from danger while traveling.

This story about beryl appeared in Rock & Gem magazine. Click here to subscribe. Story by Richard Gross & Pam Freeman.

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Beryl Colors and Names https://www.rockngem.com/rock-science-the-colors-of-beryl/ Mon, 07 Mar 2022 13:00:09 +0000 http://www.rockngem.com/?p=6867 Beryl colors are varied and include aquamarine, morganite and heliodor, despite their different, respective blue, pink and golden-yellow colors. Beryl, or beryllium aluminum silicate, is a cyclosilicate (ring silicate) that crystallizes in the hexagonal system, usually as six-sided, short-to-long prisms with distinctive flat or modified-flat terminations. Strong atomic bonding provides beryl with a substantial Mohs […]

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Beryl colors are varied and include aquamarine, morganite and heliodor, despite their different, respective blue, pink and golden-yellow colors.

Beryl, or beryllium aluminum silicate, is a cyclosilicate (ring silicate) that crystallizes in the hexagonal system, usually as six-sided, short-to-long prisms with distinctive flat or modified-flat terminations. Strong atomic bonding provides beryl with a substantial Mohs hardness of 7.5-8.0, which suits it well for gem uses.

Light-Reflecting Properties

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Beryl is an allochromatic, or “other-colored”, mineral in which the presence (or absence) of traces of chromophoric (color-causing) elements create seven distinct color varieties. Numerous channels within beryl’s ring-type, sheet structure accommodate these chromophores, which include divalent and trivalent ions of iron and manganese, and trivalent ions of chromium and vanadium. Ions of these divalent chromophores partially replace beryl’s divalent beryllium ions, while trivalent chromophores partially replace its trivalent aluminum ions. These replacements alter the light-reflecting properties of the crystal lattice to produce beryl’s wide range of colors.

Goshenite is beryl’s colorless variety. Lacking a distinctive color, goshenite is rarely used as a gemstone today, although it was once a popular substitute for diamond. Goshenite is believed to contain elemental impurities that inhibit the color-producing effects of accessory chromophores.

Emerald heads the list of beryl’s colored-gem varieties in both recognition and value. Its rich, green color is due to trivalent chromium ions that replace some of beryl’s aluminum ions. The distinctive green color of some emeralds is caused by trivalent vanadium ions replacing aluminum ions.

Green, But Not an Emerald Connection

Emerald usually occurs only as small crystals and tends to be heavily flawed, with cracks and inclusions that compromise both its transparency and its structural integrity. Nearly flawless emeralds are rare; “clean” stones with deep color and minimal flawing are extremely valuable.

Green beryl is a pale-green variety that gemologists do not equate with emerald. Its pale color is caused by divalent iron (ferrous) ions and trivalent iron (ferric) ions partially replacing beryl’s beryllium ions and aluminum ions. Because of its pale, often “muddied” color, green beryl has never been a popular gemstone.

The most popular of the beryl gems is aquamarine. Its name stems from the Latin aqua marina, literally meaning “seawater” and referring to its blue color, which is created when divalent iron ions partially replace beryllium ions. Aquamarine typically has water-clear transparency; it is also relatively abundant and occurs in large crystals that can be faceted into gems of 10 carats or larger. Aquamarine’s gem value is based not on size, but on the intensity and purity of its blue color, degree of transparency, and lack of inclusions.

Beryl’s ‘Warmer’ Side

Morganite is the pink variety of beryl. Its soft colors, ranging from pink to purplish-pink and orange-pink, are due to divalent manganese ions that partially replace beryllium ions. Morganite was named for American financier and noted gem collector J. Pierpont Morgan (1837-1913) at the suggestion of America’s first gemologist, George Frederick Kunz (1856-1932). Morganite gems have excellent transparency. Because large crystals are fairly common, morganite is often cut into gems that are 5 carats or larger.

Heliodor, beryl’s golden-yellow variety, can also be lemon yellow to brownish-yellow and greenish-yellow. The word “heliodor” stems from the Greek words helios, or “sun”, and doron, or “gift.” Its literal meaning, “gift of the sun” refers to its warm colors, which are created when trivalent iron ions replace aluminum ions.

Distinctive and Dynamic Colors

Red beryl is the rarest of beryl’s color varieties. Its saturated red color with hints of orange or purple is created when trivalent manganese ions partially replace aluminum ions. Like emerald, red beryl is heavily included and subtransparent and occurs only in small crystals.

Whether the gem is the green emerald, blue aquamarine, pink morganite, or golden-yellow heliodor, it owes its distinctive color to beryl’s ability to accommodate accessory chromophoric ions of chromium, vanadium, iron and manganese.

This story about beryl colors previously appeared in Rock & Gem magazine. Click here to subscribe. Story by Steve Voynick.

The post Beryl Colors and Names first appeared on Rock & Gem Magazine.

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