Early History & Techniques
Ancient sources of emeralds are shrouded in myths and legend. In antiquity it was believed that many improbable locations were the source of their emeralds. The Muisca of Colombia considered them to be an ancestor to their tribe. The Muzo mines have a legend about Fura and Tena, with them being lovers staying forever young in the forest so long as they were faithful. After many centuries, Fura fell in love with another and aged when Tena saw her again. Immediately knowing of the infidelity, Tena killed himself and Fura wept tears of emeralds over the tragedy. Hence the divided mountain peaks of Fura and Tena where the emeralds are found. According to the Persian polymath al-Biruni (973–1048 C.E.):
“Storytellers say about Dhu al-Qarnayn that when he entered the dark region of the world, the stones under the hoofs of the horses (of his army) began to crack. He, thereupon, told his friends that these stones were the stones of repentance. Anyone who picked them up would repent of his deed and he who would leave them alone, would also grieve. Some of his companions picked them up and some did not. When they came to the bright region of the world, they saw that they had picked up emeralds. Those that had picked them felt rueful that they had not picked more of them and those that had not, also regretted at not having picked them. Precious emeralds are, therefore, associated with the ziihnat (darkness at the extremity of the world) and it is said that the emeralds that are in the possession of people are the same that had been picked up there.”
The earliest known source of “emeralds” were located in Egypt, though they may have been peridot mines instead. Distinction between different green gems in antiquity was limited, with all green gems otherwise known as emeralds.
The famous Egyptian emerald mines, also known as Cleopatra’s emerald mines, were the world’s primary source of emeralds until significant deposits were discovered in the Americas in the 16th century. Egypt’s emerald region consists of two mining areas, Sikait and Zabara, which are located in about 40 square miles of inhospitable desert east of Aswan between the Nile and the Red Sea.
Emeralds were mined in this area from at least 2000 B.C. and nearly all of the emeralds known to the ancients came from this source. The location of the mines was lost during the Middle Ages, and not rediscovered until 1818. Although the mines are now depleted and largely abandoned, large numbers of emeralds were once found in mica schists of metamorphic origin. Another ancient source of emeralds was located in Austria and mined by the Romans. The Austrian emerald mines were worked sporadically through World War I, but are no longer commercially viable.
Process for Mining Emeralds
Knowledge of the chemistry and geology of emeralds has enabled better understanding of them and somewhat predict where deposits might be. Ancient Egyptian mines and the mines of the New World were rife with superstition and myth. According to Desautels (1970): Mad’ûdi, an Arab author of the 10th century, describes an odd belief that the Mount Zabarah emeralds (of Egypt) were found in quantities depending on the seasons, prevailing wind direction, and other atmospheric conditions, and that the intensity of their color changed with phases of the moon.
These factors do not impact actual gem-forming conditions. Emeralds found solid host rock are referred to as primary deposits. Emeralds found away from their source in river gravels and streambeds are called secondary deposits. The distinction is important because the vast majority of emeralds are found with their host rock, rather than away from it. This is because they have a similar density to most other rock and gems, which makes it hard for them to collect in specific locations.
Emerald Mining Techniques by Region
Egypt – While they were active, the Sikait and Zabara mines of ancient Egypt were worked by slaves, convicts, and prisoners-of-war. Life at the mines was harsh due to drought and climate extremes from bone-chilling nights and scorching days.
Most of the mine entrances have been closed, though the tunnels extend up to 240 meters (800 feet) into the hills. With the scarcity of wood, stone pillars were used to shore up the tunnels. Once a worthwhile pocket of emeralds were located, the tunnels became large chambers capable of accommodating mining teams.
Colombia – Mining techniques in Colombia have evolved over the centuries. Emerald deposits are frequently mined by strip mining a series of terraces, a technique that has been used since before the arrival of the Spanish conquistadors in the 16th century. The Spaniards also attempted to drive tunnels into the host rock to retrieve emerald crystals, a technique that was revived at Chivor in the 1960s.
According to Keller (1990), when mine terraces are worked with strip mining methods, soft rock is removed by either hand tools or else scraped by a bulldozer. The use of dynamite is common, despite the brittle nature of emerald crystals. Emerald deposits are easy to spot as they are found in white calcite veins running through soft black shale. The workers surround the bulldozers watching for the telltale white streak of a calcite vein. Once a deposit is spotted, they work the spot to remove emerald crystals with small picks.
When emeralds are found, they are collected in bags and later sorted. While rare, the miners can miss large crystals and end up selling a bag of $5,000 emerald tailings with a $500,000 emerald inside, though do not expect this to happen often. Material that has been sorted is flown to Bogotá for grading and marketing.
Treasure-seekers often sort through the leftovers of the mining operations in hope of finding something worthwhile leftover. They skirt the mining camps, jam the streambeds, and rummage through the black shale looking for emeralds.
Conditions – Life at the Colombian emerald mines is reminiscent of the American Wild West. Although miners are paid very little, many remain on the job because one day a month they are allowed to pocket any emeralds they find, a practice called “picando”. Illicit mining, alcohol-fueled fights, gem heists, prostitutes, and an atmosphere of desperation haunt the camps where guards armed with rifles patrol the perimeter. Transportation to and from the mines is done by helicopter since the area is full of smugglers and armed guerrillas.
More recently the Colombian government has become concerned with the ecology of the Muzo and Chivor mining areas. There are efforts to shift from strip mining to underground mining. Unfortunately, the short duration of the mining concessions does not encourage lessees to develop mining techniques that can better conserve their environment.