The Mineral CALCITE
- Chemistry: CaCO3, Calcium Carbonate
- Class: Carbonates
- Group: Calcite
- Uses: In cements and mortars, production of lime, limestone is used in the steel industry; glass industry, ornamental stone, chemical and optical uses and as mineral specimens.
- Calcite's Physical Properties
-
Specimens
With calcite so abundant and so widely distributed it is no wonder that it can be so varied. The crystals of calcite can form literally a thousand different shapes by combining the basic forms of the positive rhombohedron, negative rhombohedron, steeply, moderately and slightly inclined rhombohedrons, various scalahedrons, prism and pinacoid to name a few of the more common forms. There are more than 300 crystal forms identified in calcite and these forms can combine to produce the thousand different crystal variations. Calcite also produces many twin varieties that are favorites among twin collectors. There are also phantoms, included crystals, color varieties, pseudomorphs and unique associations. There simply is no end to the varieties of calcite.
There are several varieties of calcite and it would be impossible to
describe them all. However there are a few standouts. Possibly the most
well known of calcite's varieties is its most common form, the classic
scalenohedron
or "Dogtooth Spar" as it is sometimes called. This variety
appears as a double pyramid or
dipyramid,
but is actually a distinctly different form. The point of the scalenohedron
is sharp and resembles the canine tooth of a dog, hence the name. Beautiful
clear colorless or amber-orange examples of this variety are considered
classics and outstanding examples come from Pugh Quarry, Ohio;
Not necessarily a variety of calcite, cave formations are certainly a unique aspect of calcite's story. Calcite is the primary mineral component in cave formations. Stalactites and stalagmites, cave veils, cave pearls, "soda straws" and the many other different cave formations that millions of visitors to underground caverns enjoy are made of calcite. It is the fact that calcite is readily dissolved that these formations occur. Overlying limestones or marbles are dissolved away by years and years of slightly acidic ground water to percolate into the caverns below. In fact the caverns themselves may have been the result of water dissolving away the calcite rich rock. As the calcite enriched water enters a relatively dry cavern, the water starts to evaporate and thus precipitate the calcite. The resulting accumulations of calcite are generally extremely pure and are colored if at all, by very small amounts of iron or other impurities.
Mexican onyx is a variety of calcite that is used extensively for ornamental purposes. It is carved into figurines and is so popular that almost every child in the USA owns a small onyx animal or two. Carvings such as vases, bookends, plates, eggs, obilisks, pyramids and statues are all popular. It is not the same onyx as the quartz variety of onyx which is a little more precious (it is used in jewelry) and is banded white and black. To avoid confusion it is best to refer to it as Mexican Onyx. Mexican onyx is banded with multiple orange, yellow, red, tan, brown and white colors that have marble-like texture. The carvings are quite attractive and affordable; a rare combination!
Another variety is the so called "Iceland Spar", which is basically clear cleaved fragments of completely colorless (ice-like) calcite. Originally discovered and named after Eskifjord, Iceland where the calcite is found in basalt cavities. In rock shops around the world, iceland spar is available in large quantities and at affordable prices and are popular among children. Most of today's iceland spar comes from Mexico. The iceland spar displays the classic cleavage form of calcite, the rhombohedron. Iceland spar was and is used for optical equipment and during World War II it was a strategic mineral as it was used for the sighting equipment of bombardiers and gunners. It is iceland spar that best demonstrates the unique property of calcite called double refraction.
Fluorescence,
phosphorescence,
thermoluminescence
and
The best property of calcite is the acid test.
Why? Because
calcite always will effervesce (bubble) when even cold weak acids are placed
on specimens. Even the cement in sandstones will effervesce assuring the
geologist of identification of the cementing mineral. The reason for the
bubbling is in the formula below:
The carbon dioxide gas (CO2)
is given off as bubbles and the calcium dissolves in the residual water.
Any acid, just about, can produce these results, but dilute hydrochloric
acid or vinegar are the two recommended acids for this test. Other carbonates
such as dolomite
or siderite
do not react as easily with these acids as does calcite and this leads
to differentiating these somewhat similar minerals more readily.
Calcite is intricately tied to carbon dioxide in another way. Since many sea organisms such as corals, algae and diatoms make their shells out of calcite, they pull carbon dioxide from the sea water to accomplish this in a near reverse of the reaction above. This is fortuitous for us, as carbon dioxide has been found to be a green house gas and contributes to the so called "green house gas effect". Environmentally then, calcite is very important and may have been quite important to the successful development of our planet in the past. By pulling carbon dioxide out of the sea water, this biological activity allows more of the carbon dioxide in the air to dissolve in the sea water and thus acts as a carbon dioxide filter for he planet. Environmentalists are now actively engaged in determining if this activity can be increase by human intervention to the point of warding off the "green house gas effect". A significant amount of calcite precipitation in sea water is undoubtedly inorganic, but the exact amount that this contributes is not well known. Calcite and other carbonate minerals are very important minerals in the ocean ecosystems of the world.
Calcite is not the only calcium carbonate mineral. There are no less
than three minerals or phases of CaCO3.
Aragonite
and
Calcite is truly one of the best collection type minerals. There are lots of interesting forms and varieties as well as colorful and beautiful specimens to collect. It is generally easy to identify using its rhomohedral cleavage, reaction to acid and double refraction and makes for a great classroom example of these properties. If it is not the significant mineral on a specimen, it might be an accessory to other wonderful minerals and only enhancing their attractiveness. With its many different forms, environments, associations and colors, a collector could never have all possible combinations of calcite covered.
PHYSICAL CHARACTERISTICS:
- Color is extremely variable but generally white or colorless or with light shades of yellow, orange, blue, pink, red, brown, green, black and gray. Occasionally iridescent.
- Luster is vitreous to resinous to dull in massive forms.
- Transparency: Crystals are transparent to translucent.
- Crystal System is trigonal; bar 3 2/m
- Crystal Habits are extremely variable with almost any trigonal form possible. Common among calcite crystals are the scalenohedron, rhombohedron, hexagonal prism, and pinacoid. Combinations of these and over three hundred other forms can make a multitude of crystal shapes, but always trigonal or pseudo-hexagonal. Twinning is often seen and results in crystals with blocky chevrons, right angled prisms, heart shapes or dipyramidal shapes. A notch in the middle of a doubly terminated scalenohedron is a sure sign of a twinned crystal. lamellar twinning also seen resulting in striated cleavage surfaces. Pseudomorphs after many minerals are known, but easily identified as calcite. Also massive, fibrous, concretionary, stalactitic, nodular, oolitic, stellate, dendritic, granular, layered, etc. etc.
- Cleavage is perfect in three directions, forming rhombohedrons.
- Fracture is conchoidal.
- Hardness is 3 (only on the basal pinacoidal faces, calcite has a hardness of less than 2.5 and can be scratched by a fingernail).
- Specific Gravity is approximately 2.7 (average)
- Streak is white.
- Other Characteristics: refractive indices of 1.49 and 1.66 causing a significant double refraction effect (when a clear crystal is placed on a single line, two lines can then be observed), effervesces easily with dilute acids and may be fluorescent, phosphorescent, thermoluminescence and triboluminescent.
- Associated Minerals are numerous but include these classic associations: Fluorite, quartz, barite, sphalerite, galena, celestite, sulfur, gold, copper, emerald, apatite, biotite, zeolites, several metal sulfides, other carbonates and borates and many other minerals.
-
Notable Occurrences include Pugh Quarry, Ohio; Rosiclare, Illinois;
Franklin,
New Jersey; Elmwood, Tennessee; Brush Creek and other Missouri,
Wisconsin, Kansas and Oklahoma localities, USA; Andreasburg, Harz
Mountains
and Saxony, Germany; Brazil; Guanajuato, Mexico;
Cornwall, Durham and Lancashire, England; Bombay area of India; Eskifjord, Iceland; many African localities as well as others around the world with their own unique varieties. - Best Field Indicators are crystal habit, reaction to acid, abundance, hardness, double refraction and especially cleavage.
 Amethyst Galleries' Mineral Gallery MINERALS |
CALCITE specimen cal-4$ 600.00
Dims: 15" x 6-3/4" x 4-3/4"
Wt: 30 lbs
1100 foot level, Brushy Creek Mine, Reynolds Co., Missouri, U.S.A.
This is it: the largest and highest quality specimen of the Brushy Creek Mine Calcite that I've seen, and it kicks some serious mineralogical heinee! (how the heck do you spell that word?) It is rife with phantom calcite, twins, and the most colorful Marcasite of our selection. Easily a museum-quality piece, one had better have a good bit of spotlighted space to do it justice. The crystals range in length from 1/2 inch to 7 inches, and have some truly bizarre forms.
cal-4 ($600.00)1100 foot level, Brushy Creek Mine, Reynolds Co., Missouri, U.S.A.
CALCITE specimen cal-36
$ 93.00
$ 93.00
Dims: 5.0" x 3.8" x 1.4" (12.7 x 9.6 x 3.6 cm)
Wt: 7.30 oz. (207.1 g)
1100 foot level, 106 Drift, Brushy Creek Mine, Reynolds County, Missouri, U.S.A.
This specimen is basically a triangular section of a crust which is made up of intergrown Calcite scalenohedrons. They range in length from 0.1 - 1.1" (0.3 - 2.8 cm) and have excellent form. Less than half of the crystals are covered with a crust made up of tiny marcasite crystals that are dull red, green, and gold in color. The uncovered ones have a pearly luster and dim transparence. Phantoms made of layers of microscopic marcasite crystals give them a gray coloration, whereas deeper phantoms have the visible sparkle of larger marcasites. The Calcites are aligned at random angles, and damage is limited to the crystals on the immediate edge of the crust.
cal-36 ($ 93.00)
1100 foot level, 106 Drift, Brushy Creek Mine, Reynolds County, Missouri, U.S.A.
CALCITE specimen cal-38
$ 320.00
$ 320.00
Dims: 8.4" x 6.0" x 5.6" (21.3 x 15.2 x 14.2 cm)
Wt: 3 lbs., 2.0 oz. (1.417 kg)
1100 foot level, 106 Drift, Brushy Creek Mine, Reynolds County, Missouri, U.S.A.
A magnificent specimen, this piece is composed of dozens of scalenohedral Calcite crystals that are intergrown, forming a crust. They have excellent form, and damage is noticeable but mostly limited to crystals on the edges of the piece. All the crystals but one range from 0.1 - 1.8" (0.3 - 4.6 cm) in length. The largest crystal far exceeds that, with dimensions of 5.0 x 3.2 x 2.0" (12.7 x 8.1 x 5.1 cm); it stands nearly straight up, towering over the rest of the crust. A few of the crystals scattered in the crust are coated with a thin crust made up of tiny, colorful marcasite crystals which make them sparkle. Most, however, are not, and have a pearly luster and are faintly translucent. They contain phantoms< that are made of layers of microscopic marcasite crystals, which give the Calcites a gray color.
cal-38 ($320.00)
1100 foot level, 106 Drift, Brushy Creek Mine, Reynolds County, Missouri, U.S.A.
CALCITE specimen cal-42
$ 30.00
$ 30.00
Dims: 2.7" x 2.7" x 1.2" (6.9 x 6.9 x 3.0 cm)
Wt: 3.75 oz. (106.4 g)
1100 foot level, 106 Drift, Brushy Creek Mine, Reynolds County, Missouri, U.S.A.
A few intergrown, misshapen Calcite crystals make up this specimen from the American midwest. They are in the form of scalenohedrons, and the two largest crystals form a base-to-base twin that has dimensions of 2.7 x 1.2 x 1.0" (6.9 x 3.0 x 2.5 cm). They have little visible damage, though one crystal is cleaved cleanly off of the base of another, where it had formed another base-to-base twin. Their form is good, though misshapen, with well-defined edges and faces that show heavy growth-related striations and a pearly luster. The crystals are dimly transparent and have a dull yellow coloration, but appear gray due to subtle phantoming that occurs just below each one's surface. These phantoms consist of layers of microscopic marcasite crystals. There are some much larger, exposed marcasites on the specimen's edge that are colored red and blue, with their standard metallic luster.
cal-42 ($ 30.00)
1100 foot level, 106 Drift, Brushy Creek Mine, Reynolds County, Missouri, U.S.A.
CALCITE specimen cal-46
$ 37.00
$ 37.00
Dims: 2.9" x 2.0" x 1.1" (7.4 x 5.1 x 2.8 cm)
Wt: 2.91 oz. (82.7 g)
1100 foot level, 106 Drift, Brushy Creek Mine, Reynolds County, Missouri, U.S.A.
At least 20 Calcite scalenohedrons make up this specimen. They have excellent form, and damage is confined to a few areas on the edge of the crust on which they rest. The largest of these crystals measures approximately 1.2" (3.0 cm) in length; it and several others on the crust have a gray color and a pearly luster, and are dimly transparent. This transparence enables one to see subtle phantoms that are trapped just beneath their surfaces. The phantoms are made up of layers of microscopic marcasite crystals, and give the Calcites their color. The rest of the crystals on the specimen are coated with crusts of more, larger (but still extremely small) marcasite crystals, giving them a multicolored sparkle. The crystals are aligned in random directions and are intergrown, forming the crust from which they rise.
cal-46 ($ 37.00)
1100 foot level, 106 Drift, Brushy Creek Mine, Reynolds County, Missouri, U.S.A.
CALCITE specimen cal-49
$ 38.00
$ 38.00
Dims: 2.7" x 2.0" x 1.4" (6.9 x 5.1 x 3.6 cm)
Wt: 2.46 oz. (69.7 g)
1100 foot level, 106 Drift, Brushy Creek Mine, Reynolds County, Missouri, U.S.A.
Another specimen from Missouri in the U.S., this piece consists of several scalenohedral Calcites that have excellent form. One tip of one crystal is damaged, but that is all that I can see. The largest of these crystals measures approximately 1.6" (41. cm) in length. Most of the crystals have a gray coloration (caused by phantoms just below their surfaces), pearly luster, and dim transparence. Their transparence enables one to see phantoms deep inside some of the crystals that are made up of layers of small marcasite crystals. One crystal, however, shows a coating of tiny, colorful marcasites on its surface, but it is partially obscured by a gray Calcite that is growing off of and parallel to it. Other than that, all the crystals are aligned at random angles and are intergrown to form the crust that constitutes the specimen.
cal-49 ($ 38.00)
1100 foot level, 106 Drift, Brushy Creek Mine, Reynolds County, Missouri, U.S.A.
CALCITE specimen cal-57$ 105.00
Dims: 6.0" x 4.5" x 4.5" (15.2 x 11.4 x 11.4 cm)
Wt: 3 lbs., 0.7 oz. (1.381 kg)
Amax Mine, Reynolds County, Missouri, U.S.A.
This rather complex specimen consists of nearly twenty small scalenohedral "dogtooth" Calcite crystals on a rather unusual host rock. The crystals range from 0.2 - 0.8" (0.5 - 2.0 cm) in length, with the largest ones occurring in the form of base-to-base contact twins. All have excellent crystal form, and the specimen as a whole shows almost no damage. These crystals have a pale yellow coloration and a vitreous luster, and are transparent and quite clear, though the twinning plane in the twinned crystals tends to be foggy. These crystals rest on a very strangely-shaped dolomitic limestone host rock; it almost reminds me of a coral that one would find in the ocean. It is covered with very small (2 mm diameter, maximum) white dolomite rhombohedrons that are rather heavily dusted with tiny spearhead marcasite and tetrahedral chalcopyrite crystals, which do not exceed 4 mm in diameter or length. I really like specimens like this one; it has many crevices and a lot of material to examine.
cal-57 ($105.00)Amax Mine, Reynolds County, Missouri, U.S.A.
CALCITE specimen cal-69
$ 60.00
$ 60.00
Dims: 3.7" x 1.8" x 1.2" (9.4 x 4.6 x 3.0 cm)
Wt: 2.49 oz. (70.6 g)
1100 foot level, 106 drift, Brushy Creek Mine, Reynolds County, Missouri, U.S.A.
This Brushy Creek specimen consists of a crust made up of several scalenohedral "dogtooth" Calcite crystals that have excellent form and show very little damage. The largest of these crystals measures 1.3 x 0.8 x 0.5" (3.3 x 2.0 x 1.3 cm), and like several others, has smooth, clean faces (that show a bright, pearly luster), well-defined edges, and a gray coloration that is caused by phantom inclusions of tiny marcasite crystals. Other crystals in the cluster, however, are covered with larger marcasite crystals that sparkle with a metallic luster and show subtle tinges of red, yellow, and green iridescence. As far as we know, the Brushy Creek locality in the midwestern U.S. is the only locality where material of this type is found.
cal-69 ($ 60.00)
1100 foot level, 106 drift, Brushy Creek Mine, Reynolds County, Missouri, U.S.A.
CALCITE specimen cal-74
$ 55.00
$ 55.00
Dims: 4.2" x 2.1" x 1.4" (10.7 x 5.3 x 3.6 cm)
Wt: 5.34 oz. (151.5 g)
1100 foot level, 106 drift, Brushy Creek Mine, Reynolds County, Missouri, U.S.A.
This specimen consists of a crust that is made up of many intergrown scalenohedral "dogtooth" Calcite crystals that are intergrown, mostly at their bases. The cluster is in generally good condition, though there are a few areas of obvious cleavage damage. The largest of the crystals on this cluster measure not more than 1" (2.5 cm) in length. Most of these crystals have clean faces and edges that have a pearly luster and are colored gray due to the presence of microscopic marcasite crystals that are included within. However, some of the Calcites have visible marcasite crystals coating their exteriors, giving them a reddish-to-gold coloration and a metallic sparkle.
cal-74 ($ 55.00)
1100 foot level, 106 drift, Brushy Creek Mine, Reynolds County, Missouri, U.S.A.
CALCITE specimen cal-77
$ 25.00
$ 25.00
Dims: 1.7" x 1.6" x 1.1" (4.3 x 4.1 x 2.8 cm)
Wt: 1.89 oz. (53.7 g)
Naica, Chihuahua, Mexico
A bit of a mystery surrounds this specimen. It consists of a cluster that is made up predominantly of Calcite. The Calcite occurs in the form of rhombohedrons that range in size from 1 mm to 0.5" (1.3 cm) along an edge. Their color is a bright white and their luster is pearly, which makes me think that maybe these are actually crystals of ankerite, as there are also many tiny clusters of "dogtooth" Calcites scattered on parts of some of the large crystals. That is not the mystery, though. Among these large crystals, the tiny "dogtooth" crystals, and many small disphenoidal chalcopyrites that are scattered about, are some thin, bladed crystals that I cannot identify. They have what appears to be a monoclinic form, a pale beige color and a vitreous luster, and are transparent and very clear. They show no effervescence in a dilute acid, and seem to be harder than Calcite. I thought they might be siderites at first, but the form is wrong. I really am at a loss as to what they are.
cal-77 ($ 25.00)
Naica, Chihuahua, Mexico
CALCITE specimen cal-79
$ 45.00
$ 45.00
Dims: 3.4" x 3.3" x 2.3" (8.6 x 8.4 x 5.8 cm)
Wt: 15.3 oz. (434 g)
Pachapaque Mine, Ancash, Peru
This specimen contains an example of Calcite that I consider to be very pretty. The gray host rock acts as the base for many small, irregular rounded blades of Calcite. They are in very good condition, showing little human-induced damage, and do not exceed dimensions of 1.0 x 0.1" (2.5 x 0.3 cm). These blades have a bright, white coloration, are opaque, and have a dull, matte luster. Their surfaces are rough and porous-looking, and remind me very much of certain types of coral that I have seen. Actually, their similarity to coral is intense! One can tell, however, that the platelet form in which they occur has a hexagonal shape. It is possible that these platelets underwent considerable weathering or water-wear. Accompanying and often erupting through the platelets are scores of colorless, transparent prismatic quartz crystals that have good form and a surprisingly dull, waxy luster that supports my theory of weathering. There are also what appear to be many tiny pyrite crystals scattered about the piece, though their coloration is very silvery and their form does not look quite cubic- they might possibly have a high concentration of arsenic. The gray host rock on which all of this rests seems to be made up of a combination of massive Calcite and quartz.
cal-79 ($ 45.00)
Pachapaque Mine, Ancash, Peru
CALCITE specimen cal-82$ 350.00
Dims: 8.3" x 6.4" x 5.2" (21.1 x 16.3 x 13.2 cm)
Wt: 12.7 lbs. (5.8 kg)
Elmwood Mine, Carthage, Smith County, Tennessee, U.S.A.
A very large, cabinet-sized specimen, this Calcite piece is in the form that I like to call a "parallel association", wherein a group of crystals are intergrown parallel to each other, so that it one cannot call it a single crystal, nor could one call it a cluster, accurately. The association is made up of what appears to be three main crystals that have many smaller terminaions at their ends. Nonetheless, their double-terminated scalenohedral crystal form is still evident, and their form is excellent. There is substantial damage in the form of cleavage planes on three areas of the specimen, including one of the main terminations of the second-largest crystal. All of the Calcites have a beautiful golden coloration that intensifies towards their termination tips. All of the crystals are also translucent and quite cloudy at the twinning plane, and increase in clarity towards the terminations, though they never become totally clear. Their faces are clean and smooth and their terminations are well-defined, accenting the crystals' vitreous-to-pearly luster. The association is partially held together by a small amount of a gray dolomitic limestone host rock. On this host rock are several deep-brown sphalerite crystals that have a complex cube-based form and a wonderful adamantine luster. Their color is so deep that they are only dimly translucent at best, and with their luster, appear opaque. They tend to show considerable damage, as most of the visible crystals are quite exposed.
cal-82 ($350.00)Elmwood Mine, Carthage, Smith County, Tennessee, U.S.A.
CALCITE specimen cal-90
$ 25.00
$ 25.00
Dims: 4.7 x 3.6 x 1.9" (11.9 x 9.1 x 4.8 cm)
Wt: 12.8 oz. (363 g)
unknown
At least 20 Calcite crystals rest on the shale host rock of this hand specimen. These crystals reach maximum dimensions of 0.6 x 0.5 x 0.4" (1.5 x 1.3 x 1.0 cm) and are generally in very good condition, as only a few spots of damage are visible- one of these is rather severe, however. They have excellent trigonal "nailhead" form, though some of them are rather warped and others are more prismatic than tabular in nature. Most of them have a pale, rust-red coloration and are transparent and dimly to moderately clear. I think, though, that the rust coloration is caused by a thin coating over the crystals; light reflected off of their faces (which possess a pearl luster) shows iridescent red, orange, and yellow colors (see the close-up image). These crystals rest on a base of what appears to be dull brown, opaque calcite or aragonite that has an irregular, warped form. This base in turn rests on a thin crust of greenish-gray shale. I have been told that such specimens likely come from India, but the shale base makes me doubtful.
cal-90 ($ 25.00)
unknown
CALCITE specimen cal-101
$ 30.00
$ 30.00
Dims: 5.8 x 2.0 x 0.7" (14.7 x 5.1 x 1.8 cm)
Wt: 3.46 oz. (98.3 g)
unknown (likely Mexico)
This interesting specimen consists of a Calcite stalactite. It appears to be in excellent condition, though its termination tip seems to be cleaved. Even with its stalactitic form, it shows definite crystalline tendencies and even some incomplete crystal form in a few places. It has a moderate golden-brown coloration and an almost silky luster, and is mostly translucent, though its tip shows moderate transparence. There is no base or host rock present.
cal-101 ($ 30.00)
unknown (likely Mexico)
CALCITE specimen cal-105
$ 30.00
$ 30.00
Dims: 5.6 x 5.4 x 3.6" (14.2 x 13.7 x 9.1 cm)
Wt: 4 lbs., 8.0 oz. (2.042 kg)
unknown (likely Chihuahua, Mexico)
This large piece consists of a chunk of a semi-crystalline Calcite crust. It shows definite crystalline tendencies, but is also layered in areas, like marble. Its color ranges from a pale, creamy-yellow to rust-red to nearly colorless, and its uniform pearly luster was likely induced by "pickling" the piece in acid.
cal-105 ($ 30.00)
unknown (likely Chihuahua, Mexico)
CALCITE specimen cal-109
$ 60.00
$ 60.00
Dims: 11.8 x 8.0 x 2.4" (30.0 x 20.3 x 6.1 cm)
Wt: 4 lbs., 15.2 oz. (2.245 kg)
Minas Gerais, Brazil
Countless minute, tabular Calcite crystals form a large crust that covers the host rock of this large cabinet specimen. They are in surprisingly good condition- very few are visibly damaged- and generally do not exceed 0.1" (3 mm) in diameter or thickness. There are a few larger, prismatic crystals, but these are heavily intergrown with the crust and do not exceed 0.4" (1 cm) in length or diameter. All have good trigonal form with shallow pyramidal terminations. They are generally colorless and transparent, though some of the larger crystals show a milky translucence. All have a pearly luster. This crust coats a thin crust of heavily-intergrown, crysatalline quartz that in turn coats a layer of green host rock.
cal-109 ($ 60.00)
Minas Gerais, Brazil
CALCITE specimen cal-110
$ 50.00
$ 50.00
Dims: 9.9 x 5.3 x 2.9" (25.1 x 13.3 x 7.5 cm)
Wt: 5.7 lbs. (2.6 kg)
Minas Gerais, Brazil
Several large, tabular Calcites rest on the basalt base of this large cabinet specimen. They are in moderately good condition, showing considerable damage, and reach 2.8" (7 cm) in diameter. Their trigonal tabular form is highly disseminated, as if each large crystal were made up of scores of smaller, intergrown crystals that are perfectly aligned with each other. All are milky-white in color and translucent and have a pearly luster. The basalt base is coated with a thin, botryidal layer of drusy quartz, upon which the Calcites rest. A layer of the Calcite extends partway through the basalt.
cal-110 ($ 50.00)
Minas Gerais, Brazil
CALCITE specimen cal-116
$ 54.00
$ 54.00
Dims: 8.5 x 5.1 x 2.9" (21.6 x 13.0 x 7.4 cm)
Wt: 2 lbs., 1.7 oz. (954 g)
Minas Gerais, Brazil
Scores of small Calcite prisms rest on the quartz/lava base of this large cabinet specimen. These crystals generally do not exceed 1" (2.5 cm) and are in good condition, though several are cleaved and not complete. Their slim, trigonal "dogtooth" form is good, though most are at least partly intergrown with others. All are nearly milky-white in color and have a dull pearly-to-waxy luster, and most are dimly transparent. They rest on a base that is made up of alternating layers of crystalline quartz and green lava rock.
cal-116 ($ 54.00)
Minas Gerais, Brazil
CALCITE specimen cal-117
$ 150.00
$ 150.00
Dims: 8.5 x 5.6 x 1.7" (21.6 x 14.1 x 4.4 cm)
Wt: 4 lbs., 0.8 oz. (1.837 kg)
Sterling Hill Mine, Ogdensburg, New Jersey, U.S.A.
This flat cabinet specimen is made mostly of massive, white Calcite. The Calcite shows no definite crystal form and actually has a creamy coloration. It serves as the matrix for several spots of willemite and one straight vein that runs completely through the piece. The willemite does appear to be crystalline to a degree and has a color that ranges from a reddish-brown to a pale, rusty orange. When bathed under shortwave UV light, however, the calcite glows a slightly dim, orange color and the willemite glows bright green. When the UV light is suddenly switched off, the willemite phosphoresces - this means that the willemite continues to glow green for a while after the UV radiation is removed.
cal-117 ($150.00)
Sterling Hill Mine, Ogdensburg, New Jersey, U.S.A.
CALCITE specimen cal-119
$ 39.00
$ 39.00
Dims: 4.2 x 3.1 x 1.0" (10.6 x 7.9 x 2.5 cm)
Wt: 7.4 oz. (209 g)
Winfield, Pennsylvania, U.S.A.
This flat hand specimen consists of a Calcite druse that partly covers a shale base. The druse is made up of many crystals that do not exceed 3 mm in diameter. They are in good condition and well-formed, and show a dull, creamy coloration and dim transparence. They are accompanied in places by several clusters of white, radiating strontianite needles. These needles do not exceed 0.4" (1.0 cm) in length and are in good condition where they are protected by hollows and overhangs. When viewed under either long- or shortwave UV light, the Calcite glows a with a dull yellow coloration and the strontianite glows with a white color.
cal-119 ($ 39.00)
Winfield, Pennsylvania, U.S.A.
CALCITE specimen cal-120
$ 39.00
$ 39.00
Dims: 3.7 x 2.8 x 1.5" (9.5 x 7.1 x 3.9 cm)
Wt: 8.2 oz. (232 g)
Winfield, Pennsylvania, U.S.A.
A vein of crystalline Calcite runs through the shale host rock of this piece. The crystals do not exceed 0.1" (3 mm) but appear to be well-formed. Though most of the exposed ones are damaged, many are protected in hollows. All have a dull, cream coloration and are dimly transparent. A few clusters of radiating strontianite needles are also present. When viewed under UV light, the Calcite glows with a dull yellow color and the strontianite shows up as a brighter white.
cal-120 ($ 39.00)
Winfield, Pennsylvania, U.S.A.
CALCITE specimen cal-122
$ 80.00
$ 80.00
Dims: 4.1 x 2.5 x 1.4" (10.5 x 6.4 x 3.6 cm)
Wt: 4.98 oz. (141.3 g)
1100-foot level, 106 drift, Brushy Creek Mine, Reynolds County, Missouri, U.S.A.
This hand specimen consists of a cluster of partly-intergrown "dogtooth" Calcites. These crystals are in excellent condition, showing almost no damage, and reach nearly 1.5" (3.8 cm) in length. All have excellent trigonal form. Most are coated with a thin druse of tiny marcasite crystals, giving them a dull golden color and a metallic sparkle, but some are uncovered and have a gray color due to included marcasite and a dull pearly luster. There is no host rock present.
cal-122 ($ 80.00)
1100-foot level, 106 drift, Brushy Creek Mine, Reynolds County, Missouri, U.S.A.
CALCITE specimen cal-126
$ 26.00
$ 26.00
Dims: 1.6 x 1.5 x 0.4" (4.1 x 3.8 x 1.0 cm)
Wt: 19.0 g
not yet determined
This piece is more of a jewelry piece than a collector piece, I think, and was originally sold as "drusy quartz". While there is some quartz in it, most of the larger crystals are made up of flat, "nail-head" Calcites that are generally in good condition- there are a few spots of obvious damage, however. The Calcites are colorless, moderately transparent, and show a pearly luster. Their trigonal form is quite good, considering their intergrowth. They rest among what appear to be several rounded formations of drusy quartz. The sparse base rock is cut flat and ground smooth.
cal-126 ($ 26.00)
not yet determined
CALCITE specimen cal-130
$ 65.00
$ 65.00
Dims: 5.0 x 2.0 x 1.0" (12.8 x 5.0 x 2.6 cm)
Wt: 2.95 oz. (83.9 g)
1100 foot level, 106 drift, Brushy Creek Mine, Reynolds County, Missouri, U.S.A.
A cluster of well-formed Calcite prisms makes up this small cabinet specimen. These crystals do not exceed 1.0" (2.5 cm) in length and show excellent trigonal form and little damage. Some of them are covered with a thin layer of marcasite, giving them a metallic sparkle. Others are not covered, and have a gray color due to phantom layers of marcasite within. There is no host rock present.
cal-130 ($ 65.00)
1100 foot level, 106 drift, Brushy Creek Mine, Reynolds County, Missouri, U.S.A.
CALCITE specimen cal-131
$ 76.00
$ 76.00
Dims: 4.5 x 3.1 x 1.6" (11.5 x 7.9 x 4.0 cm)
Wt: 7.9 oz. (225 g)
1100 foot level, 106 drift, Brushy Creek Mine, Reynolds County, Missouri, U.S.A.
This small cabinet specimen consists of a cluster of prismatic "dogtooth" Calcites that are generally in excellent condition. The largest of these crystals is very exposed and measures 2.0" (5.2 cm) in length. It and the other crystals have excellent form. Some of the crystals are coated with a thin marcasite druse, giving them a colorful metallic sparkle. Those that are not covered contain phantom layers of the marcasite, which give them a gray color. There is no host rock present, and the base of the specimen is made up of the intergrown bases of the crystals.
cal-131 ($ 76.00)
1100 foot level, 106 drift, Brushy Creek Mine, Reynolds County, Missouri, U.S.A.
CALCITE specimen cal-132
$ 145.00
$ 145.00
Dims: 7.8 x 4.9 x 2.6" (19.8 x 12.5 x 6.6 cm)
Wt: 1 lb., 5.9 oz. (621 g)
1100 foot level, 106 drift, Brushy Creek Mine, Reynolds County, Missouri, U.S.A.
Scores of trigonal "dogtooth" Calcites are intergrown to form this display piece. These crystals reach over 2.1" (5.4 cm) in length, are in excellent condition, and have excellent trigonal form. Some have a gray color and a pearly or greasy luster, and contain visible marcasite phantoms, whereas the rest are simply coated with druses of marcasite, giving them a colorful metallic sparkle. They are intergrown at their bases to form the crust from which they extend.
cal-132 ($145.00)
1100 foot level, 106 drift, Brushy Creek Mine, Reynolds County, Missouri, U.S.A.
CALCITE specimen cal-133
$ 26.00
$ 26.00
Dims: 2.4 x 1.9 x 0.7" (6.1 x 4.8 x 1.8 cm)
Wt: 1.23 oz. (35.0 g)
unknown
Many stubby, trigonal Calcites rest on the quartzite base of this flat hand specimen. These crystals do not exceed 0.1" (3 mm) in diameter or length and are in very good condition, showing little damage. Their trigonal form is good, and their luster is greasy. All are colorless, transparent and dimly clear. They are accompanied by many small, rounded nodules of what appear to be drusy psilomelane, and the quartzite base has been cut flat- thus the piece can be used in jewelry.
cal-133 ($ 26.00)
unknown
CALCITE specimen cal-135
$ 26.00
$ 26.00
Dims: 3.8 x 2.1 x 1.7" (9.5 x 5.3 x 4.3 cm)
Wt: 8.45 oz. (239.6 g)
Amax Mine, Reynolds County, Missouri, U.S.A.
Several small Calcite prisms extend from the dolomitic limestone base of this large hand specimen. Though two of the crystals are broken and incomplete, the rest are undamaged and in good condition, showing excellent trigonal form. Their color is a rather dull, creamy-yellow, and their luster is a dull pearly. All are dimly transparent. They are accompanied by hundreds of tiny, white dolomites, scores of small chalcopyrites and several marcasite nodules that have likely pseudomorphed into pyrite.
cal-135 ($ 26.00)
Amax Mine, Reynolds County, Missouri, U.S.A.
CALCITE specimen cal-138
$ 25.00
$ 25.00
Dims: 1.0 x 0.9 x 0.8" (2.5 x 2.3 x 2.0 cm)
Wt: 9 g w/ foam base
1100-foot level, 106 Drift, Brushy Creek Mine, Reynolds County, Missouri, U.S.A.
This thumbnail piece consists of a cluster of small, scalene "dogtooth" Calcites. These Calcites are in excellent condition - only one shows slight damage at its tip - and reach 1.1" (2.8 cm) in length. All have very good trigonal form and contain included layers of tiny marcasite crystals- a few of the crystals are coated by layers of marcasite that show red and green colors and a metallic luster. The rest show the gray color and pearly luster of the calcite. There is no host rock, and the piece is affixed inside a plastic thumbnail box.
cal-138 ($ 25.00)
1100-foot level, 106 Drift, Brushy Creek Mine, Reynolds County, Missouri, U.S.A.
CALCITE specimen cal-139
$ 25.00
$ 25.00
Dims:3.7x2.5x1.6" (9.4x6.4x4.1 cm)
Wt: 6.7oz. (191g)
Reynolds cty., Missouri
At least two dozen well-formed prismatic crystals of calcite form a crust on the top of this specimen. These crystals reach 0.7" (1.8cm) in length, and show excellent termination faces. This is an aesthetic specimen of a common mineral. The only damage to this specimen is around the edges, where it was broken away from the host rock.
cal-139 ($ 25.00)
Reynolds cty., Missouri
CALCITE specimen cal-140
$ 52.00
$ 52.00
Dims: 3.62x2.28x2.01" (9.2x5.8x5.1cm)
Wt: 9.40oz (266.0g)
Coahuila, Mexico
This hand specimen of calcite is not well-shaped, although it is crystalline showing cleavage planes. It is a rather unattractive off-white in color, with some mauve and a brown dusting. But under ultraviolet light, it comes alive. Under various wavelengths, it looks yellow or even pink, and under short-wave UV it glows a bright blue, a color which remains (briefly) after the light is turned off (it is phoshorescent).
cal-140 ($ 52.00)
Coahuila, Mexico
CALCITE specimen cal-141
$ 38.00
$ 38.00
Dims: 3.85x1.53x0.92" (9.78x3.88x2.32cm)
Wt: 3.62oz (102.4g)
Level 670, La Sirena mine, Guanajuato, Mexico
This specimen displays calcite crystals against a pyrite druze backdrop. The calcite is colorless and transparent, but a finely striated surface (somewhat reminiscent of a cat's tail in shape) obscures the interior and creates a slightly milky appearance. While the overall crystal is round in cross section, there are several small attached rhombic calcite crystals with are transparent and display a vitreous luster. The pyrite druze consists of tiny cubic crystals with a slightly irridescent blue appearance.
cal-141 ($ 38.00)
Level 670, La Sirena mine, Guanajuato, Mexico
CALCITE specimen cal-142
$ 30.00
$ 30.00
Dims: 3.77x1.82x1.09" (9.59x4.62x2.77cm)
Wt: 3.30oz (93.5g)
Hechi, Guangxi, China
This is a relatively unusual specimen of calcite, in that it's color is a lovely pale green and it is at least slightly transparent with good crystals that are relatively flat with definite striations. The color does vary a bit from crystal to crystal, and the striations and translucency gives these crystals a nearly silky luster.
cal-142 ($ 30.00)
Hechi, Guangxi, China