Emerald Growth in Parallel
A Red Emerald does not grow as a single unit, but is the result of thousands of hexagonal beryl molecules deposited in groups at different locations over a surface, building in size until they merge together to form a complete mineral layer. Layers are stacked one on another, allowing a crystal to increase in size and form glassy faces. Each layer is always "under construction" to some degree, so every crystal has a surface texture or Topography.
A flat surface does not exist in nature! No matter how beautifully polished smooth a surface appears, there is still micro-topography. All surfaces have micro-topography no matter how flat they look. Atomic force microscopy can determine atomic vertical and lateral positioning with better resolution than the atomic level.
~ John Rakovan - 2016 Dallas Mineral Symposium
Scanning Tunneling Microscopy - Atomic Scale
Two layers of silica growth on the grid of an octahedral lattice
The surface topography of a mineral is the historic preservation of the exact moment formation stopped -- the instant a solution no longer remained sufficiently saturated for crystallization to continue. Scanning tunneling microscopy allows for observation of individual hexagonal molecules and layers on the atomic lattice. This information can be used to create detailed elevation maps of mineral surfaces, and the study of these topographies allows scientists and gemologists to better understand conditions under which crystals form.
The hexagonal stacking observed on the surface of certain red beryl termination ends is an indication of Growth in Parallel. Beryl molecules bond together with the least resistance by aligning side-to-side and end-to-end. These connections point all faces the same direction, the molecules are Parallel to one another, and their uniform Growth follows the same vector, called the C-Axis.
Sketch of Hexagonal Groups growing in parallel on the surface of Emeralds originating from the Otero Muñoz mine in Colombia
Growth in Parallel is a characteristic trait of Emerald -- identical molecular units stack in hexagonal groups until a mineral tower is formed. Hundreds (if not thousands or millions) of these six-sided structures are constructed in the same location, at the same time, using the same lattice, which creates interior architectures that overlap and reinforce one another.
When beryl molecules operate as a group, their original combined boundaries leave relics during growth which are preserved inside a crystal's lattice. These relics are often admired as fields of fingerprints or angular planes within a jardin, but these historic frameworks can occasionally be observed in facial topography, as well.
Growth around a Stair-Step may leave surface Etching to reveal the staggered layers still prominent within the interior crystal structure
Even heavily-included beryl varieties, such as low-grade Aquamarine, lack traditional Emerald geometries because they form in low-pressure environments. Red and Green are the only two beryl which must adapt to pressurized conditions. Their habits manage the presence of inclusions using the exact same alterations to crystal structure (covered extensively in The Pink Portfolio). These geometries prove Green and Red Emerald to be mathematically equivalent.
Constrained growth in parallel with a heavy load of impurities shaped the recognizable, classically-modified Emerald form. Incorporating additional foreign minerals and more inclusions into the molecular order of a mineral requires a greater number of "adjustments" to the standard arrangement.
Foreign minerals cause "errors" in crystal structure order, seen as dislocations, diverted growth vectors and disturbed topographies
While some "adjustments" or "errors" can be corrected with continued crystallization, certain dislocations do not disappear, forcing subsequent hexagonal groups to attach "out of parallel" with orientations slightly-askew. If additional beryl molecules expand from these canted foundations, secondary growth may create a Sidecar, Twin or Cluster specimen.
Emeralds crystal structures are commonly modified to accommodate ever-present inclusions, regularly propagating new growth -- this makes Emerald specimens some of the most complex geometric forms in the mineral collecting world!
Although disruptions to mineralization are possible, continued molecular stacking over a prolonged period typically results in the formation of a single, larger specimen. Even a crystalline red beryl specimen weighing less than 1/10th of a carat is one of the purest forms of one of the rarest minerals on Earth! These Micro-Specimens are the smallest existing units for collectors to appreciate the natural wonder inside Red Emeralds.
Hexagonal groups initially form a mineralized layer used as a foundation for further growth. As this base enlarges, the mineral becomes a thickened plate of gem material. Whenever a crystal is flattened (broad and thin), the habit is categorized as Tabular.
A tabular specimen rarely appears flattened parallel to the C-Axis, but early-stage beryl development is identified by habits with sides shorter than the width -- these forms are referred to as Wafer specimens.
A wafer becomes a Square Prism when the length of a habit's sides equals the width. This equilateral outline of a mineral in this shape presents a box-like or cubic appearance.
When a mineral's sides lengthen to exceed the width of its crystal structure, this habit has become a Rectangular Prism. Some of the most breathtaking red beryl specimens are in the form of these hexagonal towers.
Anhedral - no planar surfaces or observable ordered mineral formation
Subhedral - development of at least one crystal face, but less than all
Euhedral - a crystal bounded by faces on all sides
A perfectly-formed Euhedral habit for red beryl is double-terminated -- composed of two flat termination ends with six glassy faces.
Solid-phase crystallizations are often Subhedral, lacking complete structures because of a failure to fully replace the host mineral. Faces can also be lost from corrosion or replacement with a subsequent mineral.
Different minerals can compete during formation, and homogeneous crystals can grow against one another, impeding smooth surface formation to produce an Anhedral mineralization.
The limitations of three dimensions make it impossible to simultaneously view more than four sides (3 faces and 1 termination) of an unmodified, euhedral hexagonal prism. Because of this, even with only two to three fully-formed faces, a subhedral red beryl crystal can often be photographed aesthetically to appear euhedral, or pictured with a sufficient number of faces so one may imagine the specimen with a complete euhedral form.
Compared to all other minerals, the formation of even a single red beryl crystal face in this universe is an INCREDIBLY RARE affair!!! A crystal face is a sign of highly-ordered molecular structure, a well-formed mineral and a work of natural art worthy of admiration.
I attempt to preserve every subhedral red emerald crystal in the hopes this helps improve our collective understanding of Earth's rarest precious gemstone variety!