Emeralds are in no risk of falling out of favor if their history is any indicator. Mined as early as 2,000 BC, they were avidly collected by Eastern potentates and warlords, who were often one and the same. They still boast devoted fans today. Scientists reveal that emeralds have been twinkling underground for roughly the last 3 billion years. But accessing them was and remains the big deal.
Ancient emerald mines like the primordial ones of northern Egypt were sometimes in fact peridot mines. Egyptians conscripted prisoners, slaves, and other unfortunate souls to dig tunnels into hills known to harbor the glittery green bits. Pillars of stone erected at various junctures propped up the tunnels long enough for workers to ferret out the coveted green crystals.
Making the Separation
But green was green in those days, and gems lacked any scientific way of separating similarly colored stones. Even when excavators struck upon green “emerald” veins underground, much of their booty would be considered green beryl by today’s picky standards. Separating green beryl from emerald (which is also beryl) requires a sophisticated method of detection rather than simply a visual identification.
Sorting Out the Greenies
Green beryl classified as emerald requires the inclusion of coloring agents chromium or vanadium (or a combination of both). If a crystal is designated as green beryl on the other hand, it contains iron for its coloring agent. Some emeralds have traces of iron which lends a yellowish tint to the stone – but they predominantly have chromium and or vanadium as their coloring source.
When the Spaniards landed in Colombia in the 16th century, they implemented a primitive form of terrace mining – strip mining, if you will. But they discovered that the technique was already in use by indigenous locals.
Today’s modern emerald mining methods can include the application of dynamite in a procedure called D & B for drilling & blasting, or with high-pressure water. That’s a proven method for releasing crystals from its matrix. Concussive efforts used in this extraction process for emeralds often produce the iconic branch-like inclusions called jardin (for garden) within the rough.
Modern Emerald Sources
Despite all that romantic history of early Egyptian mining, emeralds are not really mined there anymore. Places like Colombia, (providing 70-90% of the global output) Brazil, and Zambia account for commercial supplies of emerald today. Zambia especially has become an exciting source of this material.
Not just any terrain can produce emeralds. The region’s geology and its conditions must be very specific. There are 2 main ways under which emeralds form. The first is when superheated water is combined with necessary mineral elements under conditions of exacting pressure. These geological conditions produced Colombian emeralds. The second way emeralds were formed was in an environment which cooled mineral-rich magma (molten rock) underground instead.
Super-Size it Please!
Emerald’s formation in matrix often yields small-sized rough from either pegmatite deposits or hydrothermal veins in metamorphic rock. So recent news of a gigantic emerald discovery has been especially thrilling. Gemfields Group, a global source of gemstones with a dominant presence in Africa, recently announced the sale of its “massive emerald cluster” the Kafubu Cluster found at its Kagem Emerald Mine in Zambia in 2020.
Kafubu Emerald Cluster
Considering its size of 187,775 carats, it’s no wonder experts were abuzz worldwide. Inspecting the mammoth rough also revealed it had very little matrix, something of a rarity with sizable emerald crystals. Gemfields referred to the spectacular find as its Gentle Giant. While it maintains a policy of not reporting sales figures of individual items in their auctions, Gemfields did say that the Kafubu Cluster is the most expensive emerald ever sold by the mining conglomerate.
“The total auction revenues of $30.8 million, from 34 lots sold, helped push Kagem’s total auction sales in 2022 to a ‘record shattering’ $149 million – up from a $92.3 million record set in 2021,” according to Mining.com. The Kafubu Cluster alone represented 44% of the total emerald weight offered at that auction, Gemfields said.
The Perfect Conditions
With such a spectacular find, it’s worth examining the geology that yielded such a rarity. Zambia’s Kagem Mine has evolved into one of the most important emerald recovery sites in the world. Within this rich copper-bearing terrain, Zambian emeralds prove to be some of the oldest on earth, some 500 million years old. Zambian emeralds have developed in this rare combination of 1.6 billion year old high-grade metamorphic rock (Talc Magnetite Schist or TMS) plus the younger 500 million year old intruding pegmatite.
Despite all the hubbub surrounding the massive Kafubu Cluster, it’s not the only remarkable emerald to be extracted from Kagem recently. Some other colossal crystals have been brought up from the lucrative mine, including a 3 pound specimen found in July 2021. That one was 7,525 carats and named Chipembele, a Bantu word meaning rhino, owing to its similarity to that animal’s horn.
Gemfields London-based boss Sean Gilbertson is optimistic about the company’s performance against a down turned global landscape. In CITYA.M., November 7, 2022, Gilbertson reportedly said he considers such gemstones to be resistant even in the current economic climate. “There is something to be said for people having a proclivity for an object of value, that is directly with them and very personal. It is not going to be blown up with their pension in the event some trader hits the wrong button.”