Zambian Emerald Specimens
Ever since humankind began culling gemstones for a myriad of purposes—to adorn the body, as a talisman ornament, even for an accompaniment on the journey to the afterlife, for example—so have people been collecting mineral specimens.  Not only are mineral specimens extraordinarily beautiful, but also they are enduring, making the collection of these prized possessions an easy objective.   What makes them so fascinating is that they are a completely natural occurrence, something fashioned as a result of both the passage of time and geological processes underground.

Minerals are the building blocks of rocks, yet they can be as glorious as lavender fluorite, as intense as red spinel, or as enchanting as emerald crystal.  Each and every mineral maintains a distinctive chemical composition and unique physical properties; therefore, no two minerals are alike, although the atomic structure of each mineral never varies.  A mineral specimen is considered to be a solid substance containing a crystalline structure.  Over four thousand valid mineral species have been categorized, according to the International Mineralogy Association. 
Because so many species exist in the Mineral Kingdom, specimen collectors often concentrate on one area of interest, although often many collectors will forgo specialization and seek out those rare and exquisite pieces they wish to obtain. 

Because mineral specimen collectors prize minerals in their pure and natural form, when evaluating a piece, collectors follow three simple rules of the trade:  Seek out completely unadulterated minerals; examine the rarity of them; and consider the aesthetics, including color.  As it is akin to the business of art collecting, for specimen collectors, the finer the piece, the rarer the material, the more intense the color, and the better the clarity, the more enticing it is.

Although individuals have long been collecting mineral specimens, the business of merchandizing them is rather new, as is the specialization of companies in the field.  The practice of merchandizing began sometime in the 1960s, following an interest in the trading of quartz crystals from Arizona (which led to what is now one of the largest annual gem and mineral shows of its kind).   Today it is a thriving industry, and collectors often acquire their specimens through mineral dealers, who purchase specimens through private tenders.

Owing to the rarity of certain mineral specimens, in addition to the singular uniqueness of each piece, certain specimens are in greater demand than others.  One mineral specimen that, when found to be of the highest quality, is very rare and highly significant is that of the Zambian emerald.  The specimen-quality crystals produced by the Kagem Emerald mine in Zambia happen to be some of the finest connoisseur-quality mineral specimens.  This area produces crystals that exhibit an intense classic emerald-green color with outstanding luster, and occur in wonderfully contrasting white quartz or black phlogopite mica. In addition to this, some of these happen to be very large—with some crystals measuring up to 10 cm in length and 2.5 cm in width—an attribute not generally found in emerald specimens. 

Emerald mineralization in the Kafubu area (the district in which the Kagem mine is located) occurs in mica-rich reaction zones (2 meters wide) along contacts of pegmatites and quartz-tourmaline veins, with the host Talc-Magnetite Schist.  The schist contains 3000-4000 ppm of Chromium, providing the amount of Chromium necessary for the rich-green color of the emeralds.  The quartz-tourmaline veins and pegmatite dikes in the Kafubu area are genetically related to a granite pluton at depth.

Potassium/Argon dating of the muscovite associated with emerald (beryl) crystal growth in the Kafubu reaction zones suggest an age of crystallization of approximately 450 million years ago.  Emerald specimens from this area occur in two distinct environments. Reaction zone areas with relatively less quartz contain a solid phlogopite (black) mica matrix within which emeralds are imbedded.  The mica-rich reaction zone is 5 cm to 20 cm thick.  Emeralds range in quality from gem clear to almost completely replaced with mica. Specimens from this quartz deficient zone are referred to as "Mica Schist Hosted."

Some portions of the reaction zones are much wider than the mica-rich areas.  These wider areas form voids or pockets where large emeralds can form. Quartz flooding within the reaction zones fills these pockets thus protecting any emeralds that may have formed within them.  The pockets can reach over 30 cm in width. Emeralds within these quart-protected pockets are typically of extreme high quality as they contain few mica inclusions.  Emerald specimens from this quartz-rich zone are referred to as "Quartz Hosted."

Interestingly enough, extraction of emerald specimens from the Kagem mine only began of late.  From the onset of mining in Zambia in 1928, crystal production didn’t occur until some eight decades after operations initially began.  As such, no significant quantity of specimen-quality crystals were saved during this period; however, in 2008, an unusually thick zone of quartz was discovered, yielding three significant pieces of quartz within which were several gem-quality emerald crystals.  As a result, Gemfields, which owns the mine in partnership with the Government of the United Republic of Zambia, sought Collector’s Edge Minerals, a third-party specimen recovery and preparation company, to prepare and market the stones for gem buyers and collectors.  The resulting specimens debuted in 2009. 

Although a cumbersome casing, had the thick quartz coating not surrounded the crystals, the emerald specimens would not have been preserved.  Indeed, removal of the quartz is time consuming and demanding, but it is well worth it, for it yields rather breathtaking results, proving yet another exciting find in the world of mineralogy and the realm of specimen collection.
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