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Stone Mountain Turquoise - Information
From a common definition, turquoise is a hydrous phosphate of aluminum and copper, Al2(OH)3PO4•H2O+Cu.
However, Stone Mountain Turquoise has very unique combinations of minerals that produce many various colors, shapes and sizes of turquoise. The rock formations in the area have been studied vigorously over the years,
andesite-rhyolite, limonite, porphyry iron, hornblende quartz monzodiorite, argillaceous, and carbonate sedimentary rocks including evaporites on some mountain peaks are but a few.
These rock formations went through many different changes throughout pre-historic periods. Some were gradual and others abrupt and violent. Often times we find blended rock formations that appear to be burned, melted then pressured into to a crystaline structure. We also find formations that might be considered to be "mineral vugs".
We consistantly find two types of turquoise, "turquoise nuggets" and "vein turquoise".
We also have found many other materials that don't seem to fit with any obvious classification. To name a couple that is, Botryoidal Turquoise and Intrusive Quartz Turquoise.
The Botryoidal Turquoise typically runs within mud viens that is compacted into large cracks of the overall base rock.
(For access to more information about "Botryoidal Crystals, please visit our references below)
The Intrusive Quartz Turquoise is a very rare occurance that we have been finding since the early 1980's when we first started the dig. This type of material runs quartzy knobs. This material produces some of our hardest turquoise.
(For access to more information about "Intrusive Quartz, please visit our references below)
The Translucent Turquoise is our rarest material, and was the some of the first material that was first found in the early 1900's, then later claimed by Godber. Some time after Godber abandoned the claim, material was found in 2-3mm slabs of semi-translucent material within the same vicinity.
(For access to more information about "Transulcent Turquoise, please visit our references below)
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Vein Turquoise:
A good majority material we have discovered is "vein turquoise". Thickness typically ranges from 1mm up to 30+mm on larger slabs.
Here is a common dimension for vein turquoise fom Stone Mountain:
25x30x3-4 mm
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Our smallest slabs can be near, 10x5x2 mm and our largest slabs are much larger, 145x70x20 mm (plate-like material)
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Nugget (Vug) Turquoise:
About 20% of the material we find is in a nugget shape. Here is common shape and size for our nugget turquoise,
29x20x6-10 mm
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Botryoidal Turquoise:
A rare find at Stone Mountain is "Botryoidal Turquoise",
This type of turquoise is formed by Botryoidal Crystal formations that form in large cracks. Mud veins within the cracks have voids that can fill with rich minerals then later forming turquoise. After a long period of time, the low pressure within the crack can urge the forming stone to its atomical shape.
The majority of this material is considered to be Sub-Botroydial, because the stone was restricted in shape on one or more sides of the stone.
Some of this interesting material resembles a frog skin or toad skin texture.
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Intrusive Quartz Turquoise:
Among our rarest and hardest material forms in large voids within a rock structure
that consists of porphyritic quartz monzodiorite and monzonite or a Plagioclase feldspar.
The feldspar usually bears a white to beige colored matrix with white quartz crystals
that are imbedded within the stone.
The material that forms in the porphyritic quartz monzodiorite and monzonite
usually bears an orange to dark red color within dense quartz crystal clusters
that are can be intrusive or extrusive.
Our Quartzy Turquoise is usually blue, although on occasion we do find green with
quartz, typically the shape is blocky and thick. (up to 30-40 mm)
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Translucent Turquoise:
The finest grade material we have ever seen! This material is absolutely remarkable... It generally runs in thin veins of varying colors, a good majority of the translucent material is a beautiful Blue-Green color. Much of the translucent turquoise runs within cracks near large quartz knobs that are speckled throughout the deposit. There is always an exception though, we sometimes find translucent material that is botroydial, quartzy or even blocky. We had a Gemology done in 1987 by, Allen E. Lombardo. He found that our midgrade material had varying translucence. We found that to be very interesting back then, and since that time we have discovered a larger variety of translucent material. Hold one of these slabs up to your standard desk lamp and you will see what we mean.
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Reference Sources:
Turquoise Mineral Data
Area Mineral Findings
Mineral Vugs
Botryoidal Crystals
Sub-Botroydial
Plagioclase Feldspar
Porphyritic Quartz Monzodiorite
Intrusive & Extrusive Quartz
Translucent Turquoise
Allan E. Lombardo Gemology - Page 1 - Page 2 - Page 3
To see the Material in this gemology click here
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