MINERAL SPECIMENS FOR SALE ~ Cal  Neva Mineral Company
   
 

Gallery 10  Agates, Geodes & Thundereggs

Return to Mineral Specimen Galleries

 

 


Agate, Dryhead Agate Mine, Bighorn River Area, Pryor Mountains, Carbon County, MT
click on image for larger view

AD-236  Agate (fluorescent)  $95

Dryhead Agate Mine, Bighorn River Area, Pryor Mountains, Carbon County, MT

10.5 x 8.7 x 3.1 cm

A very large & colorful sedimentary Agate from Montana. This specimen shows banding of red & several hues of orange surrounding a contrasting white core and encased in a coffee-colored matrix. The center portion of this agate also has good Fluorescence under SWUV light. Sedimentary Agates are formed in sediments as opposed to being formed by filling cavities in the rock during secondary processes in volcanic rocks. Dryhead" Agates, with their gorgeous colors and patterns locked inside the surrounding nodules, are prized by Agate collectors. The Dryhead Agates were named after many bison skulls found near the site. That was where the Native Americans were said to have run the bison over the cliff, killing many of them, and then arranging the bison skulls in ceremonial manner.



click on image for larger view

AD-188  Agate & Quartz Thunderegg  $45

Dugway Mountains District, Dugway Range, Tooele County, UT

12.3 x 7.5 x 2.8 cm

This is one of the more attractive Dugway geodes that I've encountered. This lithophysae nodule features alternating bands of blue and white and cavities lined with drusy Quartz crystals.


Agate, Steinkaulenberg, Idar-Oberstein, Birkenfeld, Rhineland-Palatinate, Germany
click on image for larger view

AD-231  Agate  $35

Steinkaulenberg, Idar-Oberstein, Birkenfeld, Rhineland-Palatinate, Germany

4.4 x 2.3 x 3.5 cm


Here's an example of something that you don't see for sale very often. An Agate from the world's most renowned Agate locality. This specimen has a pleasing and medium-blue hue with a blush of red due to inclusions of Hematite. The specimen on the right features finely banded layers of grey and off-white with a central portion of crystallized Quartz.
The area surrounding the twin cities of Idar & Oberstein gained notoriety for the fantastic Agates & Amethyst lined geodes discovered there in the mid 1500's. By the beginning of the 1800's the production of material had fallen to a small fraction of what was found in its heyday.


Agate, Horní Halže, Klášterec nad Ohrí, Krušné Hory Mountains, Ústí Region, Czech Republic
click on image for larger view

AD-150  Agate with Hematite  $75

Horní Halže, Medenec, Chomutov District, Ústí nad Labem Region, Czech Republic

12.3 x 10.4 x 3.5 cm

This Agate is unlike any I have seen from the Czech Republic.  During an early stage of its formation, membrane-like layers of minerals came off the walls of the cavity, broke and were deposited in a colloidal silica solution.  This Agate has a light-blue color that is accented by veins of silver-gray hematite that have colored the Agate red.  A very striking and eye-pleasing combination of colors.


Quartz geode, Kenfig Sands, Porthcawl, Bridgend, Wales, UK
click on image for larger view

AD-123  Quartz & Hematite geode  $60

Kenfig Sands, Porthcawl, Bridgend, Wales, UK

7.5 x 7 x 2.6 cm.

Here we have a geode that very much resembles the more famous nodules from the Dulcote Quarry which is about 30 or so miles to the southeast. This ocean front location has been known for its geodes since at least the 1800's. According to H.T. De La Beche, in his Memoirs of the Geological Survey published in 1846, he puts forth the theory that these are weathered out of the seabed offshore and wash up on the beach.


Agate, Horní Halže, Medenec, Chomutov District, Ústí nad Labem Region, Czech Republic
click on image for larger view

AD-235  Agate with Quartz  $25

Horní Halže, Medenec, Chomutov District, Ústí nad Labem Region, Czech Republic

5.7 x 6.4 x 3 cm

A colorful blue and white Agate deep red-colored dendriform inclusions.


Agate and Quartz, Amerzgane, Ouarzazate Province, Drâa-Tafilalet Region, Morocco
click on image for larger view

AD-168  Agate with Quartz  $45

Amerzgane, Ouarzazate Province, Drâa-Tafilalet Region, Morocco

9.7 x 5.2 x 4.4 cm

This is an example of one of the more colorful combinations of Agate & Quartz from Amerzgane. Bands of red and peach-colored Agate surround a center lined with crystals of Quartz. Most of the Agates that I have seen from this location have a milky-colored Chalcedony core instead of a center lined with Quartz crystals.


Agate, Steinkaulenberg, Idar-Oberstein, Birkenfeld, Rhineland-Palatinate, Germany
click on image for larger view

AD-232  Agate  $30

Steinkaulenberg, Idar-Oberstein, Birkenfeld, Rhineland-Palatinate, Germany

4.3 x 4.5 x 3.3 cm

Here's an example of something that you don't see for sale very often; an Agate from the world's most renowned Agate locality. This specimen features finely banded layers of grey and off-white with a central portion of crystallized Quartz. The area surrounding the twin cities of Idar & Oberstein gained notoriety for the fantastic Agates & Amethyst lined geodes discovered there in the mid 1500's. By the beginning of the 1800's the production of material had fallen to a small fraction of what was found in its heyday.



click on image for larger view

AD-185  Amethyst geode  $65

Idar-Oberstein, Birkenfeld, Rhineland-Palatinate, Germany

7.6 x 5.9 x 3.7 cm

Here we have a German classic, one half of an Almond-shaped, Amethyst geode from Idar-Oberstein. This example features Chlorite-dusted crystals measuring up to 1.2 cm in size. The area surrounding the twin cities of Idar & Oberstein gained notoriety for the fantastic Agates & Amethyst lined geodes discovered there in the mid 1500's. By the beginning of the 1800's the production of material had fallen to a small fraction of what was found in its heyday.


Amethyst and Chalcedony geode, Dugway Mountains District, Dugway Range, Tooele County, Utah
click on image for larger view

AD-145  Amethyst & Chalcedony geode $50

Dugway Mountains District, Dugway Range, Tooele County, UT

10.1 x 7.3 x 2.6 cm

This is one of the more colorful Dugway geodes that I have come across in my 30+ years of collecting.  What you typically get with a Dugway are washed out earth tones and if you are lucky, light blue Chalcedony and some small crystals of Quartz.  This multi-chambered nodule has a good red-brown hue accented by bands and areas of green with a central chamber of rich-colored Amethyst.  Amethyst is rarely found at this locality.



click on image for larger view

AD-198  Agate  $60

Amerzgane, Ouarzazate Province, Drâa-Tafilalet Region, Morocco

10.4 x 4.5 x 5.0

A blue-grey & white-hued Agate that exhibits a great parallax. This specimen could easily be mistaken for a Laguna Agate, that's how strikingly it “winks”. A parallax is an effect which is sometimes referred to as “winking”. When a banded Agate forms with close alternating opaque and transparent bands, the light entering the Agate can cast an observable shadow from one opaque band onto the next. As the parallel bands change their perceived angle, the appearance of movement and perception of depth occur. The finer the banding, the more striking this effect is.



click on image for larger view

AD-165  Agate & Quartz Thunderegg  $120

St. Egidien, Glauchau, Zwickau, Saxony, Germany

16.6 x 14.2 x 7.3 cm

A large specimen from Germany's premier thunderegg locality. The dense banded outer layers of deep-blue grades to a sky-blue core. This colorful thunderegg also features several small pockets of Quartz.



click on image for larger view

AD-166  Agate & Quartz Thunderegg  $65

Mount Airy Mine, New Pass District, Lander County, NV

14.2 x 13 x 4.9 cm

Resembling the more famous St. Egidien nodules this specimen features bands of blue-colored agate wrapped around a core of tightly-packed Quartz crystals. This specimen has been polished to a good lustre. Specimens from this remote locality are hard to come by even for us local collectors.



click on image for larger view

AD-177  Smoky Quartz geode  $50

Mooralla, Southern Grampians Shire, Victoria, Australia

5.7 x 5.5 x 3.9 cm

Inside a Quartz crystal-lined rhyolite geode are two intergrown crystals of Smoky Quartz. 25-30 years ago these were fairly common but lately the trend seems to be to bust up the geodes so that the Smoky Quartz crystals are fully exposed on just a fragment of matrix. These specimens are classics for Australia.


Chalcedony variety Jasper, Cairo, Egypt
click on image for larger view

AD-105  Chalcedony variety Jasper  $50

Cairo, Al Qahirah Governorate, Egypt

7.5 x 6 x 2 cm.

When I was in Egypt in April 2010, I saw many nodules of Jasper and Chalcedony just lying around on the ground out in the desert near Cairo.  I wondered why no one has ever offered this material for sale.  In 2011, while at the Tucson show, I was fortunate enough to run into a dealer who had some of these nodules for sale.  I made a trade with him for two of these specimens.  It was explained to me that these colorful nodules are difficult to polish.  Jasper is a dense, opaque, microcrystalline variety of Quartz. Or more strictly; Chalcedony and is usually red, brown or yellow and coloured by Iron oxides.  I think I chose some good ones, with nice earth-colored tones and interesting banding.  One thing that I have noticed in my many years of collecting is that there is not too much available when it comes to Egyptian minerals.  These colorful Chalcedony nodules are sometimes called “Sahara Agate”.


JChalcedony variety Jasper, Cairo, Egypt
click on image for larger view

AD-106  Chalcedony variety Jasper  $60

Cairo, Al Qahirah Governorate, Egypt

7.8 x 5.9 x 2.1 cm.

When I was in Egypt in April 2010, I saw many nodules of Jasper and Chalcedony just lying around on the ground out in the desert near Cairo.  I wondered why no one has ever offered this material for sale.  In 2011, while at the Tucson show, I was fortunate enough to run into a dealer who had some of these nodules for sale.  I made a trade with him for two of these specimens.  It was explained to me that these colorful nodules are difficult to polish.  Jasper is a dense, opaque, microcrystalline variety of Quartz. Or more strictly; Chalcedony and is usually red, brown or yellow and coloured by Iron oxides.  I think I chose some good ones, with nice earth-colored tones and interesting banding.  One thing that I have noticed in my many years of collecting is that there is not too much available when it comes to Egyptian minerals.  These colorful Chalcedony nodules are sometimes called “Sahara Agate”.


Agate, Agate Creek, Etheridge Shire, Queensland, Australia
click on image for larger view

AD-230  Agate  $35

Agate Creek, Etheridge Shire, Queensland, Australia

5.8 x 4 x 3.3 cm

An example of Agate from Australia's premier Agate locality, Agate Creek. This example features dense banding with hues of greens and yellows that are highlighted by a vivid orange-colored outer portion.



click on image for larger view

AD-176  Agate  $50

Wave Hill, Victoria-Daly Region, Northern Territory, Australia

6.5 x 5.7 x 3.5 cm

A vividly-colored Agate from down under. this specimen features alternating copper-colored bands of Agate with a white core. this Agate has a good parallax. When a banded Agate forms with close alternating opaque and transparent bands, the light entering the Agate can cast an observable shadow from one opaque band onto the next. As the parallel bands change their perceived angle, the appearance of movement and perception of depth occur. The finer the banding, the more striking this effect is.


Chalcedony geodeChalcedony geode
click on image for larger view

AD-164  Chalcedony geode  $60

Turtle Mountains, San Bernardino County, CA

7.5 x 5.1 x 4.7 cm

A Chalcedony geode from the southeastern corner of the Mojave Desert. This geode is light-pink in color and features a swirling, ribbed pattern on its translucent exterior. The face of this Chalcedony geode has been polished. Specimens from this location are hard-won and not common, especially ones with any color at all.


Opal nodule, Spencer Opal Mine, Spencer, Clark County, Idaho
click on image for larger view

AD-143  Opal nodule  SOLD

Spencer Opal Mine, Spencer, Clark County, ID

8.4 x 7.7 x 6.1 cm

When you think of American Opal, the Virgin Valley in Nevada is usually the first to come to mind.  This specimen hails from America's other large Opal location, Spencer, Idaho.  With a population of 38, it is home to one of the largest Opal deposits in the United States.  This is one of the most vividly colored Opals of this size that I've seen from this location.  While the center of this nodule is opaque, the rest of the specimen more than makes up for this.  This colorful Opal nodule has a strong saturation of color, more than my photographic skills can capture.  Broad flashes of green, blue, violet and a little red can be seen no matter how the nodule is oriented.  The Opal at this mine are contained in a Rhyolite and Obsidian flow with abundant gas pockets. Hydrothermal fluids from hot spring activity filled the pockets with both common and precious Opal.  A colorful specimen that is sure to brighten up any mineral display.



click on image for larger view

AD-175  Amethyst geode  $45

Nosy Varika, Vatovavy Fitovinany, Madagascar

11.5 x 8.2 x 5.0 cm

A peculiarly shaped geode from a recent find in Madagascar. This specimen features a thin rim of Agate and a 4.5 cm vug lined with crystals of Amethyst.


Agate & Amethyst geode, Ametista do Sul, Rio Grande do Sul, Brazil
click on image for larger view

AD-149  Agate & Amethyst geode  $80

Ametista do Sul, Rio Grande do Sul, Brazil

9.1 x 10.5 x 9.2 cm

I acquired this Agate about 10 or so years ago from a friend who imports a lot of material from Brazil.  I chose it because I had never seen one of this particular color that had an Amethyst vug at its center.  And I have yet to see another like it.  It was only recently that it dawned on me that I had seen this material, but it had been made into spheres. Which might explain why I had only seen this one intact geode half.


Chalcedony, Agate and Quartz, Potato Patch, Imperial County, CA
click on image for larger view

AD-126  Chalcedony, Agate and Quartz geode  $60

Potato Patch, Hauser Beds, Palo Verde Mountains, Imperial County, California

12.5 x 10.4 x 4.7 cm.

While once abundant, the days of easy digging at the Potato Patch are over.  This location has long been a favorite spot to collect and has been hit hard over the years.  These days there is not much to be found there.  This example of Chalcedony, Agate and a little cit of coarsely-crystallized Quartz is classic, older material that Agate & Thunder-egg collectors hold in high regard.



click on image for larger view

AD-194  Agate & Quartz with Goethite  $45

Estacion Ojo Laguna, Municipio Ahumada, Chihuahua, Mexico

6.2 x 4.8 x 3.1 cm

A white and grey-hued agate with a center portion of crystallized Quartz that has a dendritic growth of the mineral Goethite. The goethite adds color, providing a nice contrast of colors.



click on image for larger view

AD-178  Quartz geode  $65

Juchem Quarry, Niederwörresbach, Herrstein, Birkenfeld, Rhineland-Palatinate, Germany

9.8 x 9 x 9.6 cm

A cavernous specimen of Quartz from the famous Steinbruch Juchem near Idar-Oberstein.  The Quartz crystals on this specimen are included by Goethite making them appear to be smoky in color. there is a small aperture in the rear of the specimen which helps illuminate this geode's interior.



click on image for larger view

AD-181  Agate Thunderegg  $40

Agate Creek, Etheridge Shire, Queensland, Australia

10 x 6.7 x 2.4 cm

A vividly-colored lithophysae (thunderegg) Agate from Australia. The bands of Agate in this nodule are a deep, red-orange color. I've seen a decent quantity of banded Agates from this locality but thundereggs seem to be much more elusive.


Malachite pseudomorph after Azurite, Sir Dominick Mine, South Australia, Australia
click on image for larger view

AD-114  Malachite & Azurite nodule  $35

Sir Dominick Mine, South Australia, Australia

4 x 3.2 x 2.4 cm.

An excellent, complete all-around floater, rosette-like nodule of Malachite pseudomorphing sharp, bladed Azurite crystals from the famous Sir Dominick Mine of South Australia.  This old classic Australian copper mine was active from 1862-1920.  You can see a tiny remaining spot of blue from the Azurite in the center, near the bottom.



click on image for larger view

AD-187  Agate & Quartz Thunderegg  $50

St. Egidien, Glauchau, Zwickau, Saxony, Germany

9.6 x 6.5 x 2.8 cm

This double Thunderegg specimen features bands of deep-red Agate and a core of colorless Quartz crystals in star-shaped formations. St. Egidien is considered to be Germany's premier thunderegg locality.



click on image for larger view

AD-191  Agate  $40

Dryhead Agate Mine, Bighorn River Area, Pryor Mountains, Carbon County, MT

6.6 x 6 x .8 cm

A very colorful sedimentary Agate from Montana. Sedimentary Agates are formed in sediments as opposed to being formed by filling cavities in the rock during secondary processes in volcanic rocks. Dryhead" Agates, with their gorgeous colors and patterns locked inside the surrounding nodules, are prized by Agate collectors. This one shows banding of orange-red & ochre encased in a grey-brown-colored matrix. The Dryhead Agates were named after many bison skulls found near the site. That was where the Native Americans were said to run the bisons over the cliff, killing many of them, and then arranging the bison skulls in ceremonial manner.



click on image for larger view

AD-192  Celestine & Quartz in Chalcedony geode  $40

Chalcedony Beds, San Rafael District, Emery County, UT

8.8 x 7 x 4.2 cm

A brick-colored nodule of Chalcedony that has a cavity that is lined with colorless Celestine crystals and tiny crystals of Quartz.


Agate and Quartz, Rimsberg, Birkenfeld, Rhineland-Palatinate, GermanyAgate and Quartz, Rimsberg, Birkenfeld, Rhineland-Palatinate, Germany
click on image for larger view

AD-167  Agate with Quartz  $50

Heimbach, Baumholder, Birkenfeld, Rhineland-Palatinate, Germany

8.7 x 4 x 1.7 cm

A deeply-colored agate surrounding a a group of tightly compacted Quartz crystals. In addition to its vivid red color there are swirls of brown which provide a nice contrast of colors. Agates from this locality are very difficult to come by. The area surrounding the twin cities of Idar & Oberstein gained notoriety for the fantastic Agates discovered there in the mid 1500's. By the beginning of the 1800's the production of material had fallen to a small fraction of what was found in its heyday.



click on image for larger view

AD-202  Barite nodule  $35

Col de Pré Guittard, Arnayon, Drôme, Auvergne-Rhône-Alpes, France

8.5 x 7.1 x 2.5 cm

A Septarian nodule with a core of subhedral crystals of Barite. The Barite has a mild fluorescence. Septarian nodules contain angular cavities or cracks, called “septaria”. This word comes from the Latin word septum, meaning partition.



click on image for larger view

AD-207  Agate (exhibiting displacement)  $50

Estacion Ojo Laguna, Municipio Ahumada, Chihuahua, Mexico

7.6 x 3.8 x 3 cm

A lavender-pink-colored Agate from mexico's most famous agate location. This specimen has an almost transparent body with tight banding in the center. A neat feature of this specimen is a seam running down the left side of the specimen that resulted in the displacement of a portion of the nodule.


Opal nodule, Yowah Opal Field, Paroo Shire, Queensland, Australia
click on image for larger view

AD-146  Opal nodule  SOLD

Yowah Opal Field, Paroo Shire, Queensland, Australia

6.9 x 3.6 x 1.7 cm

This striking specimen of “Yowah Nut” Opal consists of a Sandstone nodule that is permeated by Opal of many different colors that it makes for a very colorful and aesthetic specimen.  This is the first one of these that I have encountered that has a hollow center.


Agate Thunder Egg, Nowy Kosciól, Kaczawskie Mts, Lower Silesia, Poland
click on image for larger view

AD-138  Agate & Quartz Thunder Egg  $60

Nowy Kosciól, Kaczawskie Mts, Lower Silesia, Poland

8.5 x 9.3 x 4.1 cm

Here we have a multicolored Agate and Quartz Thunder Egg with a small vug at its center. The Agate portion shows fine banding with an inner rim of flame-colored Chalcedony.  Nowy Kosciól is a classic Polish locality.  Thunder Eggs such as these are highly prized by Polish Agate collectors and are rarely available outside of Europe.


Agate & Quartz geode, Valle Escondido, San Rafael Department, Mendoza, Argentina
click on image for larger view

AD-148  Agate & Quartz geode  $35

Valle Escondido, San Rafael Department, Mendoza, Argentina

5 x 4.6 x 3.8 cm

A very colorful specimen from south America's other agate location, Mendoza Argentina.  Agates from this location have a reputation for being as colorful as their Brazilian counterparts.



click on image for larger view

AD-183  Chalcedony & Quartz Thunderegg  $50

Buchanan Beds, Harney County, OR

10.8 x 9.3 x 2.8 cm

Here we have a triple-chambered thunderegg from southeast Oregon. The green-colored rind combined with the white and red-hued interior makes for a nice contrast of colors. Multiple-chambered thundereggs are uncommon, more so triple, quadruple, etc... chambered nodules.



click on image for larger view

AD-184  Agate & Quartz Thunderegg  $85

Lierbach Valley, Oppenau, Black Forest, Baden-Württemberg, Germany

19.5 x 14 x 6.4 cm

Here we have a very large section of Agate from Germany's Black Forest. The center of this slate-green-colored Agate is filled with Quartz crystals. The two chambers of this Agate have sparkling Quartz crystals and a rust-red-colored mineral, most likely Hematite. There are many Agate localities all over Germany, but few Agates ever make it to the United States.


Agate Thunder Egg, Nowy Kosciól, Kaczawskie Mts, Lower Silesia, Poland
click on image for larger view

AD-137  Agate Thunder Egg  $60

Nowy Kosciól, Kaczawskie Mts, Lower Silesia, Poland

10.2 x 9.2 x 4.4 cm.

A multicolored Thunder Egg type Agate with a hollow center from a classic Polish locality.  Thundereggs such as these are highly prized by Polish collectors and are rarely available outside of Europe.


Agate and Quartz geode, Lierbachtal, Schwarzwald, Germany
click on image for larger view

AD-113  Agate and Quartz geode  $75

Lierbachtal, Oppenau, Schwarzwald, Germany

13 x 12 x 3 cm.

Here we have a very large section of Agate from Germany's Black Forest.  The center of this slate-colored Agate is filled with Quartz crystals.  The section of this Agate that has the Quartz crystals is outlined by a red-colored mineral, most likely Hematite.  In my 23 years of collecting I have only seen one other example of this material.  There are many Agate localities all over Germany, but few Agates ever make it to the United States.


Aqate and Quartz geode, Iraí, Alto Uruguai Region, Rio Grande do Sul, Brazil
click on image for larger view

AD-118  Agate and Quartz geode  $25

Iraí, Alto Uruguai Region, Rio Grande do Sul, Brazil

6.2 x 5.4 x 4.5 cm.

While it is true that Agate specimens from Brazil are very abundant, every once in a while you find examples that are more interesting than most.  A while back, while visiting with a friend of mine that has a shop in San Diego, he showed me about 50-60 Agates that had been polished all around, not just on the front face.  As a rule, I don't buy Agates from Brazil, but I was impressed enough with what he showed me to buy a half dozen of them.  This specimen has an outer band of light- blue with a sandy-yellow colored bands, followed by clear Quartz at the center where there is a cavity lined with a druse of small Quartz crystals.  Not your everyday Agate from Brazil.


Agate with Quartz, Idar-oberstein, Germany
click on image for larger view

AD-087  Agate with Quartz  $35

Idar-Oberstein, Rhineland-Palatinate, Germany

11.2 x 7.5 x 3.5 cm.

Here's something that you don't see for sale very often. The area surrounding the twin cities of Idar & Oberstein gained notoriety for the fantastic Agates & Amethyst lined geodes discovered there in the mid 1500's. By the beginning of the 1800's the production of material had fallen to a small fraction of what was found in its heyday. This specimen features finely banded gray, white and pink Agate alternating with layers of Quartz. While occasional specimens can be found, there is no steady supply of material from this classic location.


Agate, Idar-Oberstein, Rhineland-Palatinate, Germany
click on image for larger view

AD-088  Agate  $30

Idar-Oberstein, Rhineland-Palatinate, Germany

7.2 x 5.4 x 5.6 cm.

Here's something that you don't see for sale very often. The area surrounding the twin cities of Idar & Oberstein gained notoriety for the fantastic Agates & Amethyst lined geodes discovered there in the mid 1500's. By the beginning of the 1800's the production of material had fallen to a small fraction of what was found in its heyday. This polychromatic Agate features finely banded layers of gray, white and pink making for a specimen with a striking contrast of colors. While occasional specimens can be found, there is no steady supply of material from this classic location.