Psuedomorphs & Mineral Oddities
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pseudomorph after Feldspar
Erongo Mountain, Karibib, Erongo Region, Namibia
11.8 x 6.7 x 10.2 cm
A very large and interesting pseudomorph. This three-dimensional specimen is a complete and total replacement of nine Orthoclase crystals by tiny Quartz crystals which have a green cast. Also present on this specimen are fragments of Schorl. Being someone who has an appreciation for any mineral specimen that is out of the ordinary, I fell in love with these when I first saw them. A majority of the combinations of mineral species that can be found in Erongo are quite abundant, it seems to me that Pseudomorphs are under represented at this famous location. These never were very abundant and probably won't be in the future.
with sand inclusions
Rattlesnake Butte, Jackson County, SD
6.2 x 5.5 x 2.7 cm
A sculptural pair of interconnected, scalenohedral Calcite crystals. The Calcite grew in a sand matrix, capturing the sand as it formed making for an unusual specimen. Sand Calcites are poikiloblastic Calcite crystals included by a large amount of Quartz sand, sometimes exceeding 50%. These specimens were collected heavily in the 1960s-1970s but are seldom seen these days as much of this area is within an Indian reservation and collecting is prohibited.
Pitwak Mine, Ladjuar Medam, Sar-e Sang, Koksha Valley, Badakhshan, Afghanistan
4 x 4 x 3 cm
A group of Marialite crystals from small finds made 7-8 years ago. The Marialite crystals are pseudomorphing to Orthoclase. This specimen seems to have almost completely altered to Orthoclase as very little fluorescence is observed. The blue color of these specimens is thought to be most likely due to minute Fe impurities that transition between Fe+2 and Fe+3.
Q-485 Quartz & Hematite cast after Calcite & Barite SOLD
Wölsendorf Fluorite Mining District, Upper Palatinate, Bavaria, Germany
9.3 x 7.7 x 7.2 cm
This specimen shows the scalenohedral form of the Calcite crystal that it has replaced as well as the form of the blade-like Barite crystals. The Quartz crystals on this specimen are included by Hematite which makes for a nice contrast of colors. These specimens are ucommon, rarely do you see one of these Quartz after Calcite casts from Wölsendorf offered for sale.
pseudomorph after Aragonite
Valle de las Plumas, Paso de Indios Department, Chubut Province, Argentina
9 x 7.6 x 7 cm
This group of Aragonite crystals have been pseudomorphed by Quartz, included by Hematite which gives it its reddish tone. So what you have is Quartz in the exact form of the prior Aragonite crystals, having preserved their form perfectly. There is some translucence at the terminations of the crystals. Once abundant, I don't see these for sale too often these days.
& Quartz pseudomorph after Horn Coral
Red Horn Coral Occurrence, Rileys Canyon, Woodland, Summit County, UT
8.7 x 5.2 x 2.3 cm
Here we have a polished section of Agatized red horn coral, Caninia contorta, from east of Salt Lake City, Utah. The coral is close to 350 million years old and was once buried under a layer of volcanic ash that provided the silica for the Agates that fill in the coral skeleton. Meanwhile the central part of the former calcareous skeleton has been entirely replaced by Quartz.
cast after Calcite
Artigas, Artigas Department, Uruguay
7.5 x 4.1 x 3.5 cm.
Here we have a complete all-around Amethyst cast after Calcite. This specimen consists of a tower of numerous medium-purple Amethyst crystals. If you look up the bottom of the specimen you will see the sharp, pseudohexagonal form of the dissolved Calcite crystal. The Calcite was completely etched away by corrosive solutions in the pocket, leaving the Amethyst. These specimens are one of nature's better looking mineral oddities.
Q-558 Quartz (modified by lightning) SOLD
Serra de Espinhaco Mountains, Diamantina, Minas Gerais, Brazil
12 x 4 x 3.1 cm
An example of Quartz that, inside the rock where it was formed, was submitted to a high electrical voltage created by lightning hitting the rock (not the Quartz crystal). Due to its piezoelectrical properties, the Quartz crystal submitted to this high voltage will expand or contract (depending on the signal of the electrical field, positive or negative). The result is a weird crack pattern that develops on the crystals faces of the Quartz. For many years, crystal miners in the Serra de Espinhaco Mountains of Brazil, where there are frequent thunderstorms, have reported finding these oddities. But only in the last 8-10 years have any, in limited quantities been available to collectors.
The Espinhaco Mountains are constantly affected by orographic thunderstorms, which generate a high number of lightning bolts. These orographic flashes have some special properties: they reach speeds of up to 160,000 m\s and thereby generate plasma temperatures of 30,000 ° C in nanoseconds. There is a paper about these type of crystals that was published by Prof. Joachim Karfunkel et. al., from University of Minas Gerais, who found the explanation for these weird crack patterns. You can read about it (in German) here: Link to article
pseudomorph after Apophyllite
Summer Storm Claim, Challis, Bay Horse Mining District, Custer County, ID
12.8 x 13.7 x 9 cm
A large and fully intact vug of Apophyllite crystals that have been completely replaced by Quartz. Also present in this specimen are several flattened Calcite crystals set deep inside the vug. These pseudomorphs were a limited find made by John Cornish (Rat's Nest Claim Heulandite) in the early 2000's. This was, according to the miner, the only intact vug recovered from this find.
Elbaite & Quartz on Cookeite cast after Tourmaline
Araçuaí, Minas Gerais, Brazil
12.9 x 7.6 x 5.2 cm
A vug of Cookeite that once encased a large Tourmaline crystal that dissolved away leaving a bed of greenish-blue Elbaite on the lower front portion of the specimen. The termination of this specimen features a 2 cm Tourmaline crystal that has been replaced by Lepidolite. Also present on the Cookeite “shell” are several groups of Quartz crystals.
var. Sericite pseudomorph after Tourmaline
Noyes Mountain Quarry, Greenwood, Oxford County, ME
7 x 6.8 x 6.2 cm
A good-sized Tourmaline crystal that has been partially replaced by silvery-green crystals of Sericite (a variety of Muscovite). This specimen has a shallow termination on the upper portion with a more crudely-formed termination on its bottom. The composition of the Tourmaline from this location is an intermediate between Schorl and Dravite. These specimens were collected in the early 1980's and are highly prized by collectors. This quarry was worked briefly by Loren Merrill and Arthur Valley in 1921-1922 for the benefit of Kenneth K. Landes, then a Harvard University student. Landes' dissertation, Paragenesis of the Granitic Pegmatites of Central Maine (American Mineralogist, 1925, v. 10, p. 355-411) was based on this quarry and the Bennett Quarry in Buckfield and his thesis revolutionized ideas about how pegmatites crystallize.
pseudomorph after Ikaite (Glendonite)
Carter Creek, North Slope Borough, AK
7.3 x 2.4 x 2.4 cm
A doubly-terminated pseudomorph/alteration specimen of "Glendonite" from one of America's northernmost mineral localities. These specimens start out as the mineral Ikaite which is calcium carbonate but with a handful of water molecules attached to it. Once the Ikaite reaches a temperature above 8°C (46°F), it alters to Calcite.
pseudomorph after Orthoclase
Saubachriss, Muldenberg, Klingenthal, Vogtland, Saxony, Germany
6 x 4.8 x 3.9 cm
Here we have an example of one of the more elusive pseudomorphs from Europe. A twinned Orthoclase crystal measuring 4.8 centimeters in length, that has been completely replaced by Topaz. While there is a small imperfection on one corner, this specimen is still considered an really good example of this material. Examples of this material, especially on matrix, are getting quite difficult to find these days.
with Beryl inclusion
Dara-i-Pech Pegmatite Field, Chapa Dara District, Konar Province, Afghanistan
2.8 x 2.4 x 2.5 cm.
Just when you think that you've seen it all from Afghanistan, there's this specimen A lustrous crystal of Schorl that is include by a clear, colorless Beryl crystal. The Beryl continues down the length of the specimen with a small portion protruding from the Schorl's bottom. Another neat feature of this specimen are the pronounced and well-formed growth hillocks on its beveled termination. I have sold a good amount of material from Afghanistan over the last 27 years and I have only seen one other specimen like this.
pseudomorph after Leucite (Pseudoleucite)
Kalehöyük, Kaman District, Kirsehir Province, Turkey
6.2 x 6.1 x 5.5 cm
A single equant crystal of Leucite that has been replaced by chalky white Orthoclase. A very rare and fine pseudomorph from an obscure locale.
pseudomorph after Anhydrite
Agua Fria River, New River Station Area, Yavapai County, AZ
4.5 x 4.3 x 2.6 cm
These dramatic Chalcedony pseudomorphs after Anhydrite were collected over a period of 10 years by my friend, Al Rose. This material has the distinction of being mentioned not once but twice in The Mineralogical Record's what's new in minerals. Not many of these were found and are much sought after by collectors of Arizona minerals as well as by pseudomorph collectors.
pseudomorph after Gypsum (fluorescent)
Crawford Dam, Crawford, Dawes County, NE
9.5 x 8.7 x 7 cm
Nebraska is not necessarily the first state that one thinks of when it comes to mineral specimens, but these pseudomorphs from Crawford are some of the more noteworthy specimens from anywhere in the Cornhusker State. This piece is a group of what were originally Gypsum blades that were completely replaced by Quartz. Areas of the interior portion of this specimen exhibit yellowish fluorescence under LWUV light and other areas have bright green fluorescence under SWUV illumination which suggests that specimen is made up of both Chalcedony and Quartz. Fluorescence in Quartz is rarely observed.
F-287 Orthoclase pseudomorph after Leucite (Pseudoleucite) SOLD
Loucná, Ostrov, Karlovy Vary District, Karlovy Vary Region, Czech Republic
4.3 x 4.2 x 3.9 cm
A pseudomorph of Orthoclase after Leucite with a tetragonal trisoctahedron form.
A-119 Aragonite SOLD
Wheeler Peak, White Pine County, NV
7 x 5.8 x 5.5 cm
Here we have a polished section of an Aragonite stalactite from a remote location from the easternmost part of central Nevada.
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