ROCK CRYSTAL, the clear and colorless variety of quartz

VARIETY INFORMATION:

  • VARIETY OF: Quartz , SiO 2 , Silicon Dioxide .
  • USES: Ornamental stone and gemstone.
  • COLOR: Colorless.
  • INDEX OF REFRACTION: 1.544-1.553
  • BIREFRINGENCE: 0.009
  • HARDNESS: 7
  • CLEAVAGE: none
  • CRYSTAL SYSTEM: trigonal
  • SPECIMENS

Rock Crystal is the name given to all clear colorless quartz. It is widely used as a popular ornamental stone and is also used as a gemstone. Although it is one of the least expensive gemstones, cut rock crystal has been used as imitation diamonds. Rock crystal lacks the fire, color (of course) and the rarity to be ranked as a fine precious gemstone. None-the-less, rock crystal is in wide use as a gemstone due to its beauty, affordability, availability, and ease of cutting.

The most common use for rock crystal is in ornamental carvings. A well known ornamental carving for rock crystal is the crystal ball of fortune telling fame. While rock crystal is common it is hard to find large crystals of quartz with the clarity and size required for the crystal balls that most of us associate with fortune tellers. Rock crystal is used for many ornamental carvings from spheres (crystal balls) to pyramids to obelisks to figurines to eggs to bowls to wands. There are also many fine chandeliers that are outfitted with rock crystal ornaments.

Rock crystal can have the colorless clarity of pure water, unlike ordinary window glass which is a pale green. Yet the most common flaws - internal fractures - result in veils and colorful refractions that lend beauty to an otherwise ordinary object.

Rock crystal is an alternate and traditional birthstone for the month of April. Quartz is often associated with balance, clarity, and energy.

Many people prefer uncut clusters of rock crystal. These natural treasures look like crystal cities of fantasy stories. The long slender clear prisms of quartz projecting upward from a common base are true mineralogical wonders that can be admired by all. They cost of good clusters of rock crystal is quite affordable and comes from sources around the world. The best rock crystal sources are in the famous Hot Springs area of Arkansas, USA; Cumberland, England; St. Gotthard, Switzerland; Brazil and Madagascar. Large individual crystals of quartz have been found in Brazil, the largest weighs over 44 tons.

Rock crystal often has inclusions of other minerals and these inclusions sometimes produce popular varieties of ornamental stone. Golden rutile inclusions produce a unique stone aptly named rutilated quartz that has a very hair-like look. Another apply named stone is called tourmalinated quartz and contains intricately crossing needles of black schorl tourmaline trapped in the clear crystal.

Phantoms are a result of inclusions which occur when other minerals such as chlorite, hematite or even milky quartz form as a crust on the surface of the crystals during a hiatus in the crystal's growth. The crystal then grows out and around the encrusting growth, encasing it inside. But since the thin encrustations formed over a crystal complete with crystal faces it appears that there is a crystal inside the crystal. The encrustations are often incomplete or diffuse and appear ghostly, hence the name phantom.

Rock crystal is only one of several quartz varieties. Other varieties that form macroscopic (large enough to see) crystals are as follows:

  • Amethyst is the purple gemstone variety.
  • Citrine is a yellow to orange gemstone variety that is rare in nature but is often created by heating Amethyst.
  • Milky Quartz is the cloudy white variety.
  • Prasiolite is the leek-green variety.
  • Rose quartz is a pink to reddish pink variety.
  • Smoky quartz is the brown to gray variety.
ROCK_CRYSTAL specimens:
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ROCK_CRYSTAL specimen roc-19
$ 270.00
Dims: 12.4" x 7.3" x 3.9" (31.5 x 18.5 x 9.9 cm)
Wt: 5.7 lbs. (2.6 kg)
Mount Ida, Arkansas, U.S.A.
Probably the largest cluster of our present stock, this specimen consists of a crust that is made up of hundreds of thin, hexagonal prismatic Quart crystals. The largest of these crystals extends over 3.5" (8.9 cm) out of the crust, and though it and four of the other largest crystals show slight chipping on their termination tips, there is almost no other damage. The crystals have the classic hexagonal prismatic form with steep, six-sided pyramidal terminations, and have very well-defined edges and clean, striated faces that show off their vitreous luster. All are transparent and their clarity is exceptional- I do not see any internal fractures, and cloudy inclusions are confined to the bottom 0.5" (1.5 cm) of each crystal. The close-up image shows only one end of the piece. It is really one of the finest Rock Crystal clusters that I have seen in a while!
no photo
roc-19 ($270.00)
Mount Ida, Arkansas, U.S.A.
ROCK_CRYSTAL specimen roc-21
$ 70.00
Dims: 1.6" x 1.6" x 1.0" (4.1 x 4.1 x 2.5 cm)
Wt: 1.85 oz. (52.4 g)
Ace Of Diamonds Mine, Herkimer County, New York, U.S.A.
This small specimen consists of two partially intergrown "Herkimer Diamond" Quartz crystals. Both are in good condition, showing a relatively small amount of damage, and are nearly equal in size. They have the standard chubby, double-terminated, hexagonal prismatic form that is expected of crystals from this locality, and their edges and faces are clean, showing a vitreous luster. Both are colorless and transparent, but show many inclusions, such as air bubbles, included carbon impurities, and internal fractures. I could not locate any two-phase inclusions in this piece, but I did not try very hard, and are many bubbles to examine.
no photo
roc-21 ($ 70.00)
Ace Of Diamonds Mine, Herkimer County, New York, U.S.A.
ROCK_CRYSTAL specimen roc-22
$ 75.00
Dims: 2.3" x 2.1" x 1.8" (5.8 x 5.3 x 4.6 cm)
Wt: 4.59 oz. (130.2 g)
Ace Of Diamonds Mine, Herkimer County, New York, U.S.A.
This small hand specimen consists of three intergrown Herkimer Diamond Quartz crystals. All are in very good condition, showing almost no human-induced damage. The smallest has visible dimensions of 1.2 x 1.0 x 0.9" (3.0 x 2.5 x 2.3 cm) and the largest measures 2.1 x 1.6 x 1.5" (5.3 x 4.1 x 3.8 cm). All have excellent hexagonal prismatic form and are short and double-terminated, as is common with "Herkies", and have a bright, vitreous luster. They are colorless, transparent, and only partially clear, as all contain air bubble inclusions and are highly internally-fractured. There are a few pieces of rust-stained gray limestone host rock attached to the specimen.
no photo
roc-22 ($ 75.00)
Ace Of Diamonds Mine, Herkimer County, New York, U.S.A.
ROCK_CRYSTAL specimen roc-23
$ 420.00
Dims: 5.0" x 3.4" x 1.8" (12.7 x 8.6 x 4.6 cm)
Wt: 1 lb., 11.2 oz. (771 g)
Mount Ida, Arkansas, U.S.A.
This rather large hand specimen represents one of the nicer individual Rock Crystal specimens that I have seen. It has no detectable human-induced damage. A small notch in the edge that forms the termination's tip (see the close-up image) looks obviously new, but on close examination, one can see that some partial healing has occurred before the crystal was mined. One of the prism edges is mostly gone due to the separation of a partially-intergrown crystal, and two prism faces show the presence of several smaller, partially-embedded crystals. However, the rest of the edges are well-defined and all of the other faces are quite clean, showing the standard vitreous luster. It is colorless, transparent, and quite clear, though veil-like inclusions and internal fractures increase towards the crystal's base. It stands upright on its own, and is quite impressive.
no photo
roc-23 ($420.00)
Mount Ida, Arkansas, U.S.A.
ROCK_CRYSTAL specimen roc-24
$ 80.00
Dims: 3.0" x 2.1" x 1.6" (7.6 x 5.3 x 4.1 cm)
Wt: 5.07 oz. (143.9 g)
Ace of Diamonds Mine, Herkimer County, New York, U.S.A.
Two partly-intergrown "Herkimer Diamond" Quartz crystals constitute this specimen. The larger one has dimensions of 2.5 x 1.6 x 1.1" (6.4 x 4.1 x 2.8 cm), and the smaller one measures 1.7 x 0.8 x 0.8" (4.3 x 2.0 x 2.0 cm). The smaller crystal is noticeably damaged, as the tip of its exposed termination is missing, but the larger crystal is in excellent condition, showing only a small amount of damage associated with its mining. Both crystals have a warped but definite chubby hexagonal form and are double-terminated. Their edges are straight and well-defined; their faces are clean, with only faint striations, and show a bright, vitreous luster. Both are colorless and transparent. The larger crystal is filled with intense internal fracturing that interferes greatly with its clarity, whereas the smaller crystal is much clearer and less included. There is a small amount of host rock attached to the specimen that has a pale gray coloration and shows a small amount of rust-staining.
no photo
roc-24 ($ 80.00)
Ace of Diamonds Mine, Herkimer County, New York, U.S.A.
ROCK_CRYSTAL specimen roc-25
$ 200.00
Dims: 4.5" x 2.8" x 1.5" (11.4 x 7.1 x 3.8 cm)
Wt: 11.8 oz. (335 g)
Ace of Diamonds Mine, Herkimer County, New York, U.S.A.
This beautiful hand specimen consits of 5 "Herkimer Diamonds" that are intergrown. These crystals range in size from 0.7 x 0.6 x 0.4" (1.8 x 1.5 x 1.0 cm) to 2.5 x 2.1 x 1.7" (6.4 x 5.3 x 4.3 cm) and are in generally good condition, though one of the larger crystals shows considerable conchoidal fracture damage. All show the short, stubby hexagonal prismatic form and double-terminating that is common for crystals from this locality. Their edges are straight and well-defined and their faces are clean and smooth, showing a bright, vitreous luster. All are transparent and clear, though most are considerably internally-fractured and contain many dark inclusions. The damaged crystal has a very unusual, triangular internal fracture just under the surface of one of its termination faces (see the close-up image)- I have not seen such an internal flaw as this before. Most of the crystals were separated from each other when they were mined; they were subsequently glued back together. However, this is not easily noticeable. There is only a very small amount of a rust-colored host rock present.
no photo
roc-25 ($200.00)
Ace of Diamonds Mine, Herkimer County, New York, U.S.A.
ROCK_CRYSTAL specimen roc-26
$ 620.00
Dims: 5.4" x 3.7" x 2.8" (13.7 x 9.4 x 7.1 cm)
Wt: 2 lbs., 9.4 oz. (1.173 kg)
Mount Ida, Arkansas, U.S.A.
This large hand specimen consists of 2 partially intergrown Quartz crystals, one of which makes up the bulk of the specimen. The larger crystal shows excellent hexagonal prismatic form and is capped on either end by double hexagonal pyramidal terminations. One of these terminations was obviously formed through healing after it broke off of its base; its termination faces are heavily striated and slightly curved, and separate at its tip into several smaller, uneven termainations. The other termination is obviously the original, as its faces are flat and cleaner than those of the healed termination, and they taper to a single point. The smaller crystal has a slightly warped, flattened form and shows one complete termination, which is also somewhat warped. It does show evidence of double-termination, but the second termination is missing due to a large, uneven conchoidal area of damage. This large area is surprisingly clean, though, and I thought at first that it was a naturally-created surface. Both crystals are colorless and have a bright, vitreous luster. They are transparent and tend to be clear towards their early terminations, but cloud up significantly towards their base-oriented terminations.
no photo
roc-26 ($620.00)
Mount Ida, Arkansas, U.S.A.
ROCK_CRYSTAL specimen roc-27
$ 118.00
Dims: 2.4" x 2.0" x 1.8" (6.1 x 5.1 x 4.6 cm)
Wt: 2.91 oz. (82.5 g)
Huaron Mine, Ancash, Peru
Upon first glance, this small hand specimen looks merely like a cluster of small Quartz crystals. However, close examination will reveal at least 4 Japan-Law Twins (see the close-up image) and one "V-Twin" among the singular crystals. The longest crystals on the specimen reach lengths of up to 1.0, and both of these are involved in twins. There are several broken and incomplete crystals visible on the specimen, including 2 that would have made yet another Japan-Law twin had they remained intact. However, the intact crystals show excellent hexagonal prismatic form and the vitreous luster that is standard for crystalline Quartz. All are colorless, transparent, and quite clear, though a few of the larger crystals show visible veil-like inclusions. These crystals almost completely envelop a thin slab of a gray host rock that I cannot identify.
no photo
roc-27 ($118.00)
Huaron Mine, Ancash, Peru
ROCK_CRYSTAL specimen roc-38
$ 40.00
Dims: 4.7 x 3.9 x 3.5" (11.9 x 9.9 x 8.9 cm)
Wt: 1 lb., 13.1 oz. (824 g)
Herkimer County, New York, U.S.A.
A single "Herkimer Diamond" quartz crystal rests in the sizable host rock of this hand specimen. It is in excellent condition, showing no visible damage, and has a diameter that averages 0.4 - 0.5" (1.0 - 1.3 cm) and a length that likely reaches 0.7" (1.8 cm), though not all of it is visible. It has exceptional hexagonal prismatic form, with sharp edges and clean faces that possess the standard vitreous luster. Though one end is obscured by the base rock, the crystal is likely double-terminated. It is colorless, transparent, and moderately clear, as it contains a few tiny solid inclusions and several veil-like inclusions. The dark brown host rock is made of a tough limestone that I am told is a difficult medium for amateur miners to deal with. This host rock has several pits that extend a short way into it- these pits may well have contained crystals at one time which have since been removed.
no photo
roc-38 ($ 40.00)
Herkimer County, New York, U.S.A.
ROCK_CRYSTAL specimen roc-39
$ 140.00
Dims: 4.5 x 2.9 x 2.7" (11.4 x 7.4 x 6.9 cm)
Wt: 1 lb., 3.2 oz. (544 g)
Mundo Nuevo, Ancash Department, Peru
At least 100 Quartz prisms rest on this hand specimen from Peru. These crystals range in length from 0.1 - 0.8" (0.3 - 2.0 cm) and are generally in good condition, though much breakage is visible. Those crystals that are intact have excellent hexagonal prismatic form, with well-defined edges and clean faces that possess the standard vitreous luster. Some of these crystals are nearly as thin as human hairs, and a few have a flat, almost tabular shape. Most of these flatter crystals are part of 4 Japan-Law twins that can be seen with some close examination. One of these twins is exposed and obvious (see the close-up image), but the other 3 are partly concealed by other crystals, and take a while to find. Two others existed at one time, but are now incomplete due to breakage. The Quartzes rest on a base rock that is made up of various sulfides, including pyrite, sphalerite and chalcopyrite, and more Quartz.
no photo
roc-39 ($140.00)
Mundo Nuevo, Ancash Department, Peru
ROCK_CRYSTAL specimen roc-47
$ 45.00
Dims: 4.5 x 1.1 x 0.7" (11.4 x 2.8 x 1.8 cm)
Wt: 3.33 oz. (94.4 g)
Diamantina, Minas Gerais, Brazil
A single, clear Quartz crystal comprises this specimen. It is in excellent condition, showing only slight damage on a few edges and at its termination tip, and it has excellent hexagonal prismatic form. All edges are well-defined, and all faces are generally clean. However, the faces are rather odd in the fact that most of them appear to be slightly "frosted" and not perfectly clear. They also possess only slight patterning, which is usually obvious and intense on crystals from this locality. Thus, its luster is only pearly, and one does not have a perfect view to its interior, which contains only a few small internal fractures and several very small inclusions. There is no host rock present.
no photo
roc-47 ($ 45.00)
Diamantina, Minas Gerais, Brazil
ROCK_CRYSTAL specimen roc-52
$ 35.00
Dims: 1.5 x 1.2 x 0.7" (3.8 x 3.0 x 1.8 cm)
Wt: 24 g
Herkimer County, New York, U.S.A.
This "Herkimer Diamond" Quartz specimen is in fair condition, as it is considerably damaged on one side. Where intact, it has excellent hexagonal prismatic form, with sharp edges and very clean faces that possess the standard vitreous luster. Like most specimens from this locality, this crystal is colorless, transparent, and moderately to dimly clear due to the presence of many internal fractures and inclusions. There are only a few tiny bits of a host rock stuck to its base.
no photo
roc-52 ($ 35.00)
Herkimer County, New York, U.S.A.
ROCK_CRYSTAL specimen roc-53
$ 28.00
Dims: 1.4 x 1.0 x 0.8" (3.6 x 2.5 x 2.0 cm)
Wt: 19 g
Herkimer County, New York, U.S.A.
This thumbnail specimen consists of a single, incomplete "Herkimer Diamond" Quartz crystal. Though the damage it incurred spreads over several faces, it is mostly intact and show excellent hexagonal prismatic form and double-termination. Its edges are very well-defined and its faces are very clean, possessing a bright vitreous luster. It is colorless and transparent, but is only dimly to moderately clear due to the presence of many inclusions and internal fractures. There is no host material of any sort present.
no photo
roc-53 ($ 28.00)
Herkimer County, New York, U.S.A.
ROCK_CRYSTAL specimen roc-59
$ 32.00
Dims: 2.2 x 1.4 x 1.2" (5.6 x 3.6 x 3.0 cm)
Wt: 1.45 oz. (41.2 g)
Middleville, Herkimer County, New York, U.S.A.
A single Herkimer Diamond Quartz crystal rests on the brown limestone base of this specimen. The crystal has dimensions of about 0.6 x 0.4 x 0.4" (1.5 x 1.0 x 1.0 cm) and is in fair condition, as many of its edges are chipped. Its hexagonal prismatic form is good, though slightly misshapen because of two partly intersecting crystals that were removed. It is colorless, transparent and quite clear, containing only a few internal fractures, and has the standard vitreous luster.
no photo
roc-59 ($ 32.00)
Middleville, Herkimer County, New York, U.S.A.
ROCK_CRYSTAL specimen roc-60
$ 60.00
Dims: 5.4 x 4.4 x 2.8" (13.7 x 11.2 x 2.8 cm)
Wt: 1 lb., 8.4 oz. (692 g)
Mount Ida, Montgomery County, Arkansas, U.S.A.
This cabinet specimen consists of a crust made of intergrown Quartz crystals. These crystals are generally in good condition, though the largest one and a few others are noticeably damaged. All have excellent hexagonal prismatic form and show a vitreous luster. They are colorless, transparent and generally very clear, though a few are internally-fractured or cloudy due to inclusions. Only a small amount of dull quartzite host rock is present.
no photo
roc-60 ($ 60.00)
Mount Ida, Montgomery County, Arkansas, U.S.A.
ROCK_CRYSTAL specimen roc-62
$ 46.00
Dims: 2.2 x 2.1 x 1.3" (5.6 x 5.3 x 3.3 cm)
Wt: 3.22 oz. (91.2 g)
Middleville, Herkimer County, New York, U.S.A.
Three small "Herkimer diamond" Quartz crystals rest in a hollow in this small hand specimen. These crystals are generally in good condition, though the largest one is noticeably damaged, and do not exceed 0.4" (1.1 cm) in length. Their hexagonal prismatic form is very good, though one of the crystals is somewhat warped due to intersection with another crystal that was since separated. All are colorless, transparent and very clear, and show a vitreous luster on their extremely clean faces. The host rock in which they rest is a brown limestone that is standard for this locality.
no photo
roc-62 ($ 46.00)
Middleville, Herkimer County, New York, U.S.A.
ROCK_CRYSTAL specimen roc-65
$ 32.00
Dims: 2.3 x 2.0 x 2.0" (5.8 x 5.2 x 5.0 cm)
Wt: 6.31 oz. (179.0 g)
Mount Ida, Montgomery County, Arkansas, U.S.A.
This hand specimen consists primarily of two intergrown, transparent Quartz cyrstals. These crystals are arranged not quite parallel to each other- the larger of the two has visible dimensions of 2.6 x 1.6 x 1.3" (6.5 x 4.0 x 3.2 cm). Both are in excellent condition, showing minor damage, if any, and have excellent hexagonal prismatic form. They are colorless and transparent, and show the standard vitreous luster. Both are dimly to moderately clear at their terminations, but quickly become opaque and milky-white in color due to cloudy inclusions and internal fractures. There is no host rock present.
no photo
roc-65 ($ 32.00)
Mount Ida, Montgomery County, Arkansas, U.S.A.
ROCK_CRYSTAL specimen roc-72
$ 50.00
Dims: 2.5 x 2.4 x 1.9" (6.4 x 6.1 x 4.8 cm)
Wt: 4.47 oz. (126.9 g)
Santander, Colombia
This hand specimen consists of scores of long, thin Rock Crystal quartz crystals that support 2 larger, thicker crystals. The largest of these has dimensions of 2.9 x 0.5" (7.2 x 10.3 cm), and like the others, is in excellent condition and has excellent hexagonal prismatic form. All are colorless, transparent and quite clear, though they tend to cloud slightly near their bases. The length and thinness of the smaller crystals makes them easily breakable, so care is advised in handling and storing the piece.
no photo
roc-72 ($ 50.00)
Santander, Colombia
ROCK_CRYSTAL specimen roc-74
$ 350.00
Dims: 7.04x5.35x4.00" (17.88x13.59x10.17cm)
Wt: 41.34oz (1172g)
Himchal Pradesh, India
This is a plate of heavily intergrown quartz crystals, mounted by clusters of larger prismatic quartz crystals which show excellent clarity. The quartz is completely colorless and I can detect few inclusions. The surfaces of the crystals do show fine striations and a dusting of additional minerals which prevents the crystals from appearing perfectly transparent. The specimen presents well, although there are large areas of the quartz plate with a relatively smooth surface - it looks like contact areas with adjacent minerals which were, of course, removed. A loupe reveals that the flat areas are mostly natural quartz facets (or rather thousands of tiny facets), with not very much in the way of fracture surfaces. A few of the medium sized crystals are broken, and the largest crystal has a small amount of obvious damage at its tip.
no photo
roc-74 ($350.00)
Himchal Pradesh, India

 


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