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A crystal
dendrite is a crystal that develops with a typical multi-branching
tree-like form. Dendritic crystal growth is very common and
illustrated by snowflake formation and frost patterns on a window.
Dendritic crystallization forms a natural fractal pattern.
The term
"dendrite" comes from the Greek word dendron, which means
"tree".
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Few people know that gold actually forms
crystals in nature. While the beauty of natural gold is widely
appreciated by both prospectors and mineral collectors, the pinnacle
of beautiful natural gold specimens are the spectacular crystalline
forms. As a result, these specimens of golden scales, plates, ribbons
and crystals are normally saved and treasured. Unfortunately, the
natural growth conditions that form most gold deposits only rarely
create these very attractive specimens.
Crystalline gold is the rarest and most beautiful form of gold and is
especially valued by collectors all over the world because of its
bright color and unique shapes.
At most mines, native gold is more normally found in the form of
irregular masses and blobs in quartz or sulfide veins, or as
impregnations in the country rock adjacent to mineralized fissures. In
fact in most modern hard rock mines the gold is in the form of very
tiny particles, too small to easily see with the unaided eye. In
placer gravels, the wear of the erosion process means gold normally is
pounded into the outwardly rounded forms of scales, grains, slugs, and
nuggets. While large alluvial nuggets are beautiful and valuable in
their own right, the crystalline forms are still the ones most highly
valued. In fact, the value of crystalline gold in an attractive matrix
specimen can exceed the intrinsic metal value of the gold by a factor
of 10 to 100 fold in some cases.
Although gold only rarely shows its attractive crystalline forms,
where the geologic conditions are favorable, as in cavities or other
locations where growth and expansion is not hindered by a lack of
space, gold obeys the natural laws of its crystal growth and
crystallizes in various isometric (cubic) forms. This partly explains
the rarity of fine crystalline gold specimens. This is because open
voids are uncommon in and of themselves. Normally, the walls of the
cavity limit the lines of crystal growth, or growth is cut off by the
concurrent growth of another mineral, such as calcite or quartz. Often
any voids that do exist are later filled with quartz or other
materials, including clays.
In addition, large single crystal growth requires stable conditions
that support slow growth - at least growth slow enough to lead to the
formation of a few large crystals rather than millions of tiny ones.
Faster growth will support the development microscopic pieces or at
least mossy and dendritic forms. Gold crystallizes in the isometric
system, and usually forms crude octahedrons, but specimens showing
dodecahedrons, cubes and trapezohedrons are also found. Crystals are
rarely perfect, and are normally irregular, sometimes exhibiting
unusual wiry, reticulated or dendritic shapes. Many forms also show
some sort of distortion of the crystal, some with extreme distortion.
Crystal twinning is common in gold.
Between the combined effects of all the different crystal forms,
twinning and a range of possible crystal distortions, gold can found a
very large variety of crystalline forms, all of which have their own
attractive appearance. The number of potential combinations is so
large that all the possible combinations are hard to fathom. Beautiful
wire forms are found in a number of locations, with one of the most
famous locations being Farncomb Hill in the Breckenridge District of
Colorado (beautiful leaf and other forms are found there as well).
Many of the dendritic forms are also beautiful, and one of the most
beautiful dendritic forms of gold are the herring bone style
dendrites, with some of the finest examples of this being the
"chevron" gold of northern Nevada. California produces some specimens
of ribbons and sheet gold, some with attractive crystal patterns on
their surface, and these are also highly sought after.
To learn more and see photos of beautiful natural crystal gold, see
the author's website at:
Natural Gold Nuggets - Chris Ralph |
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