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Posted by Rock Currier
Rock Currier December 28, 2008 11:36AMThis article has been prepared for the Mindat Best Minerals project. The aim of this project is to present information on important localities and specimens for each mineral specie. As new finds are made and new knowledge is made available the individual articles will be revised to include this information. Readers are encouraged to contribute by posting a response in this thread. All revisions will be stored, thus ensuring traceability and availability of previously included information. A complete list of articles can be found in the list of finished Best Minerals articles. To cite this version: Currier, Rock. (2012) Achantite. revision 1.2. Mindat Best Minerals Project, article "mesg-66-121132". Please be advised that the photos cannot be used without the consent of the copyright holder
Acanthite is the most common silver mineral and probably occurs in every silver mine in the world. It is a black mineral, but it is a black mineral made up mostly of silver! That makes all the difference in the world in the eyes of collectors. If you don’t think that’s true, ask around and see if you can find even one collector who would rather have a good augite instead of a good acanthite. What? You don’t even have an augite in your collection? You don’t even know what augite is? That’s ok, I understand.
In years past the black isometric looking crystals of silver sulfide were called argentite and were thought to be different in structure from the little pointy crystals of silver sulfide, thought to be orthorhombic, that were called acanthite. By the 1920s, it was becoming obvious that this was not the case. Ramsdele at the University of Michigan1 pointed out that angle measurements of argentite crystals were not those of isometric crystals and showed that the x-ray diffraction pattern of argentite and acanthite were the same. He speculated that argentite and a few other minerals of the galena group might be isometric only at high temperatures. Emmons, Stockwell & Jones2 showed that this was the case and that the inversion temperature was about 180° C. That left only acanthite standing as a valid species at room temperature so now curators and collectors needed to go and change the labels on all their specimens of argentite. On many specimens the label changes were not made and you will still see many specimens labeled argentite in old collections. The correct label for isometric looking crystals of silver sulfide could read acanthite pseudomorph after argentite. Since some mineralogists don’t recognize argentite to be a valid mineral species because it does not exist at room temperature they would want to see these specimens labeled simply acanthite. It all depends on what you definition of a mineral is. Yes, people are still arguing about that and every mineralogist worth his salt has a slightly different opinion.
Most acanthite crystals are not very shiny, but some of the newer specimens from the Rayes mine (not Reyes) are quite lustrous. I suspect that like many other sulfide minerals, after fifty or a hundred years, their surfaces will react with oxygen, ozone and other crud in the atmosphere and at least their surface chemistry will change and they will lose their luster. Crystals of about 4 cm are known but the best specimens have smaller crystals. Crystals of 2 cm are considered large. Most specimens of acanthite are in the 5 cm and smaller range. Larger fine specimens are rare. The best specimens of this mineral are less than 18 cm in size with sharp crystals of 1.25 cm or larger. Historically, the best specimens came from Germany and Mexico. During the last twenty years the Rayes mine at Guanajuato has weighed in again with some very fine acanthites.
Fine acanthite specimens are infrequently seen in a dealer’s stock and then perhaps as only a specimen or two. I don’t think I have ever seen a full flat of really fine acanthites except once in the inventory of Dave Bunk of Denver Colorado. Only in great museums collections are you likely to see more than one or two fine pieces. Occasionally a collector specializing in silver minerals may have several fine pieces in a drawer full of acanthite specimens, but it probably took him a lifetime to hunt them down. A fine thumbnail size acanthite specimen will probably cost you two to five hundred dollars and a good miniature or small cabinet specimen can run into several thousand dollars.
Because acanthite is a black mineral it is not easily seen in dark places like smoke filled stopes; many fabulous specimens have gone unseen, ground through mills and turned into coins. Stories of miners and dealers selling fabulous acanthite specimens for a song because they were thought to be low grade galena specimens are urban legends in the collecting community. In many silver mines acanthite has been the main ore or a major ore component and many tons of fine specimen, certainly vastly more than were saved, have been lost to the smelters.
Bohemia, Přίbram and Ratiborske Hory.
Good crystals to 2 cm as cubes or granular aggregates at Přίbram and Ratiborske Hory.1
1. Jaroslav Hyrsl, personal communication 2003.
Potosi Department, Colquechaca.
The mine at Colquechaca has produced wonderful specimens of acanthite but the locality is better known for specimens of pyrargyrite. In Quechua the word Colquechaca means Silver Bridge. The mine has produced silver for several hundred years since the time of the Spanish conquests in South America. As you enter the town, a rusty bent sign arching over the road proclaims that Colquechaca is the “Ruby silver capital of the world.” Today it is nearly moribund with a few miners trying to make a living by ferreting out scraps of high grade ore here and there in the mostly abandoned mine. The Carnegie Museum in Pittsburgh has one of the best from here with crystals of about two centimeters.
1. American Mineralogist, Vol. 10, 1925 p. 281-304. 2. American Mineralogist, Vol. 11, 1926 p.326-328.
Northwest Territories, Mackenzie District, Great Bear Lake, Port Radium, Eldorado Mine.
British Colombia, Highland Bell Mine near Beaverdell.
Here crystals of acanthite are reported to be as large as 6 cm although I have never seen any this large and think that any large crystals from here are rather poorly formed. Here small acanthite crystals commonly cover wire silver.
Ontario, Timiskaming District, Coleman Township, Cobalt, O'Brian Mine.
The mining camp of Cobalt, Ontario supported many mines, and the mines there are better known for the great masses of native silver associated with grungy looking cobalt minerals.
Ontario, Timiskaming District, Cobalt-Gowganda region,South Lorrain Township, Canadian Keeley Mine (Frontier Mine).
This mine has produced specimens with crystals up to 1.25 cm. The one pictured here is one that collectors specializing in Canadian minerals would cherish more than others.
North West Territories, Port Radium District, Echo Bay mine.
Here clusters of intergrown acanthite crystals have been found associated with chalcopyrite, calcite and quartz. Some sharp, mirror bright crystals up to 1.5 cm have been found but most acanthites from this locality are not. An 18 cm specimen of acanthite crystals from the Rod Tyson collection is pictured in the Mineralogical Record Vol. 20, p203. The crystals are neither well formed nor shiny.
Atacama Province, Copiapo Department, Chañarcillo.
In Das Mineralreich, Brauns,1903, the author states “specially fine specimens have been yielded by the silver mines at Chañarcillo, Chile.” The color plate shows images of silver minerals including a specimen of "argentite" with a well defined cubo-octahedron on calcite? The two specimens pictured here may give some idea of what some of these specimens looked like. One has a crystal that appears to be at least 2.5 cm in length and the other with slightly sharper but duller crystals of perhaps one cm, growing on calcite. Crystals from here can reach two cm and more but are not very sharp. Argentites from this locality were much more common back then than they are now. You hardly ever see an acanthite from Chile offered for sale.
Shanxi Province, Datong Prefecture, Linggiu Co., Xiaoginggou Ag-Mn deposit, Hongda Mine.
The mine is still producing specimens so we may not have seen the best specimens yet. Frequently the specimens are impressive ans some are world class. We hope to eventually have some of the better ones pictured here. But most specimens show acanthite crystals that are rather chewed up looking with tufts of wire silver growing here and there on the specimen.
Anhui Province, Chaouhu Prefecture, Lujiang Co.
Bohemia (Böhmen; Boehmen), Central Bohemia Region, Březové Hory (Birkenberg), Příbram, Anna Mine, Březové Hory deposit
Many of the silver mines in the Příbram area have been mined for several hundred years. These are very old mines, most of them long closed and inaccessible. They produced most of their specimens a century ago. You will be fortunate if you can ever get a fine example of acanthite from any Czech locality.
Limousin, Corrèze, Saint Hilaire les Courbes, Lauve
Acanthite sometimes forms thin prismatic crystals, but only in crystals of few mm. We need someone to tell us about the acanthites from this locality.
Saxony, Erzgebirge, Freiberg District.
Exceptional specimens of acanthite have been found here. The small cabinet specimen from the Smithsonian Institute collection, shown above, is a world class specimen and would probably cost more than $50,000 if sold today. The others will give you a little perspective on what good acanthites from this locality look like. Some specimens are associated with calcite and barite crystals. Notice the 10 cm specimen of lustrous acanthites from the Himmelfahrt Mine Himmelfahrt Mine. Other German localities that have produced acanthite specimens are Schneeberg, Marienberg and Johanngeorgenstadt and also in the Harz Mountains at Andreasberg. The silver mines in Germany have been operated since about the year 1200 and it is impossible to know now what the best specimens from these mines looked like. Certainly most of them were destroyed during mining and in the intervening years. Also it is entirely possible that many of the specimens attributed to the mines at Freiberg may have come from other mines but have been labeled Freiberg because the original labels were lost and Freiberg seemed the most likely locality to the collector, dealer or curator who needed to make a label for it. Look at the little beauty from the Morgenstern mine, at Freiberg with the cm size acanthite perched right on top of an amber barite crystal with others around it! “I stared…at Brückner’s other, subtler, show-stopper; a 5x6-cm, group of brilliant, stacked argentite octahedrons from Freiberg, with an old Fred Cassirer label".1 This was a description in the Mineralogical Record that is typical of the respect that advanced mineral collectors accord good acanthite specimens. Many of the old sulfide minerals are cleaned and brightened with chemical agents as much as can be managed before they are put out for sale by mineral dealers. After all, a slight increase in luster can mean thousands of extra dollars in the sale price in a fine specimen. No used car or antique dealer will sell a dirty item.
1. Mineralogical Record, Vol. 20, 1989, p 483.
Gebbard George 1988. Harzer Bergbau und Minerale. St. Andreasberg, mentions attractive cubes and octahedra of Acanthite paramorphs after Argentite to 1.2 cm from Grube Andreaskreuz, St. Andreasberg, but emphasis worthwhile specimens are quite rare in St. Andreasberg.; Baumann, Ludwig, Fritz Hoffrmann & Weber, 1997. Gluckauf, Freiberg describes and illustrates Acanthite in slender crystals to 5 cm (Grube Hymmelsfirst, and blocks of massive material to 100 kgs which sometimes were worked into coins and ornaments. Also very important find of Argentite from the intersection of Neue Hoffnung Flachen & Chrystian Stehenden in Grube Himmelfahrt in 1857. No crystal size is given but supposedly there were several hundred excellent specimens dominated by the cube with the corners cut off by octahedron and edges by dodecahedron. Arborescent and net-like aggregates, still supposedly Argentite were found as Segen Gottes in Gersdorf near Rosswein. Haake, Reiner, Siegfried Flach & Rainer Bode, 1994. Mineralien and Fundstellen. Bundesrepublik Deutschland. Claus Heidegard says he has a miniature specimen with irregular blades of Acanthite crystals to about 1 cm from Schlema.
One big big specimen from the Freiberg mining district is about 26 cm across. It is an aggregate of cm-sized cubes (acanthite paramorph after argentite). Its part of the mineralogical collection at the TU Bergakademie Freiberg. I have seen it there, together with many others. I think it is from Segen Gottes Mine, Gersdorf near Freiberg. There are tales say that at the time of duke August der Starke (August the strong) in the early 18th century they had made coins directly from acanthite, the mineral has been such frequent at that time. There have also been neat pseudomorphs of acanthite after silver wires and acanthite xls up to 6 cm formed like knife blades.
Saxony, Erzgegirge, Annaberg-Buchholz.
This specimen of Acanthite and native Silver is in the Smithsonian Institute with a Catalogue #R17303 with only Honduras as a locality listed in their catalog. One wonders what went through the crusher.
Sumatra, Bengkulu Province (Benkoelen Province; Benkulen Province),Rejang Lebong District (Rediang Lebong District).
Here acanthite specimens associated with a light pink rhodochrosite. It is only the combination that makes them interesting for neither the acanthite nor the rhodochrosite alone would be worth mentioning. I have seen very few of these specimens. Most were certainly run through the mill.
Piedmont, Verbano-Cusio-Ossola Province, Formazza Valley, Formazza, Piano dei Camosci (Pian dei Camosci)
Here is another example of thin prismatic acanthite. We need someone to tell us about the acanthite specimens from this locality. The crystals are pretty small and perhaps we should have not included this locality.
Sardinia, Nicola Secci.
This locality has produced surprisingly good acanthite specimens often growing on calcite crystals. It is certain that most of these specimens were destroyed by blasting during the mining process and went down the ore chute.
Chihuahua, Santa Eulalia.
Santa Eulalia is not well known for its silver or acanthite specimens, but this Harvard piece, while not being outstanding for either species, would certainly be a cherished specimen in anyone’s collection. Santa Eulalia, like many big long lasting mines began as a silver mine and later switched to mining copper, lead and zinc when transportation, refining efficiency and demand made it possible to mine them at a profit.
Guanajuato, Rayes Mine. (not Reyes)
This mine has been producing silver and specimens of silver minerals for the last 150 years. In 1985 and 1992 substantial finds of wonderful acanthite specimens reminded collectors that this old mine was not dead. The crystals on these specimens are mostly very shiny and show a variety of cubic habits are usually not over 1.25 cm in diameter. A fine miniature or cabinet specimen from this locality, will however, cost you several thousand dollars. Recently several miniature and small cabinet specimens of acanthite from this locality sold for a reported $8000 each. A fine specimen from this mine in the Romero collection at the University of Arizona in Tucson, Arizona is considered by some to be the finest acanthite specimen in the world and has sharp shiny crystals up to almost 7 cm. “There were more superb acanthites, pyrargyrites, stephanites and polybasites from the Reyes mine in Guanajuato. One of the acanthites found last July is nearly 7 cm on an edge and is not in the collection of Miguel Romero”1 There are many silver mines around Guanajuato and many of them are interconnected and often it is impossible to know for sure exactly which silver mine a particular specimens is from. "The Rayas mine may not be finished. Recently Great Panther Resources, a Canadian mining company, bought out the old Mining Cooperative and began development work at depth. They have encountered more rich veins and we have yet to see what specimens will be produced. La Serina, the sister mine to Reyas produced both lustrous small cubes of Argentite less than a cm and lustrous cm sized Acanthite prisms on white matrix on the same specimen showing the deposition temperature to be around 180 C".2
1. Mineralogical Record, Vol. 17, 1986, p.341. 2. Personal communication, Rob Woodside 2008.
Hidalgo, Pachuca, La Blanca Mine.
This mine has produced some decent acanthite specimens. The specimen pictured here has almost cm size, fairly well formed cubic crystals growing on small quartz crystals. The mines of the Pachuca district have produced an enormous amount of silver and comprise one of the great silver mining districts of the world.
Sonora, Arizpe, Arizpe Las Chispas Mine.
The cabinet size specimen pictured here is a world class acanthite. Sometimes this mine has been called the Pedrazzini mine because it was eventually bought by the Pedrazzini family. It has somewhat lustrous slightly skeletal octahedral crystals over 2.5 cm in diameter. I think the specimen went from Mike Redding to Bill Pinch and is now in the Canadian Museum of Natural History. I would think that such a specimen would have to bring around $50,000+ today. Jim McGlasson of Tucson, Arizona and other knowledgeable collectors think that a specimen from this mine in the collection of Miguel Romero, now at the mineral museum at the University of Arizona in Tucson, is superior to the one mentioned above. The acanthite crystals on this specimen are as large as 6 cm. It is rumored that he was offered $95,000 for the specimen in 1996.
Zacatecas, Fresnillo, San Luis mine.
This mine has produced some good acanthites but is better known for its stephanites, pyrargyrites, and polybasites. The acanthite crystals from here are smaller than 3 cm but have exceptional brilliance and some of them grow on a “white calcite that just glows”. Some people point to the published production figures of silver from Fresnillo and claim that it has produced more silver that any other silver mining district in the world, including Potosi and the Comstock. It is still going strong. We are going to see more wonderful things from this deposit. The production of silver from Fresnillo is undoubtedly great but it is a modern mine and the production figures from the older mines like Potosi are thought to be considerably short of their real production. The reason for this is that the silver from the mines were taxed by the Spanish crown so the mine owners did whatever they could to declare their production to be as small as possible. For a long time mercury was the a monopoly of the Spanish crown and the use of it by the silver mines was how the crown calculated the amount of silver a mine produced since it was the key to refining silver from the mines. It was forbidden by the crown to refine or reclaim mercury. So if native silver was found in a mine, mercury was not needed to refine it and much of it was probably melted down into bullion and never reported to the crown and certainly mercury was reclaimed when ever the mine could get away with it. All this means that the reported silver production figures of many mines was less by probably at least 50 to 100 percent than the real production. We will never know for sure.
Souss-Massa-Draâ Region, Quarzazate Province, Boumalne-Dadès, Imiter Mine.
Quite a few specimens of argentite crystals have been produced by this mine. Some weighing more than a kg. The crystals are never very shiny and few if any are very sharp. Most exhibit an octahedral crystal form. The talk about the mineral shows was that the mine was owned by the King of Morocco and that getting specimens from there was difficult and you could go to jail for a long time if caught with them. I believe most of the specimens have been worked over with an air abrasive tool to improve their surface texture which was pretty rough.
Acanthite here occurs mostly as small rough crystals associated with native silver or as a coating on native silver. Perhaps the best specimens have sharp somewhat lustrous crystals up to about a cm. There are more than 50 mines around Kongsberg, and it is rare that you will see a specimen that is attributed to a specific mine. All are now closed and many have been closed for more than 100 years. Some of the mine names you will see associated with this locality are the “Grube Else, Christian d. 6tes Grube, Gottes Hylfe in der Not or Noth Gruve (usually written as just Gottes Hylfe), Juliane Marie, Vinoren, Nye Segen Gottes No. 9, Charlotte Amalie Gruve, Christians Stoll, Jonsknut Skjerpene, Kongens Gruve, Kongens L ve, Mildigkeit Gottes Grube, Norde Vinoren, Samuel Gruve, Segen Gottes No. 9, Skara Skov.”1 . The Norwegian name for mine is Gruva but many of the miners were German and many times the German mine names and the German word for mine, Grube, was adopted by the locals and still used today.
1. Personal Communication 2002, Claus Hedegaard, Mine names represented by specimens in his personal collection.
Lima Dept., Uchuccachaqua Mine.
At least one good specimen of acanthite is known from this silver mine which is better known to collectors for moderately good, usually dog tooth shaped, rhodochrosite crystals. It was a 5x7.7 cm specimen that had a fairly shiny but not very sharp 3 cm crystal that had one largish crystal sort of buried in the matrix that measured about 3 cm in its longest direction.1 Jaroslav Hyrsl has a specimen in his collection that is pictured in Mineralien Welt of about 4x4 cm that has a fairly sharp 3 cm acanthite and also 3 cm arsenpolybasite.
1.Personal communication 2002 from Cal Graber of Fallbrook, California.
Banská Bystrica Region, Štiavnica Mts, Banská Štiavnica Mining District, Banská Štiavnica (Selmecbánya; Schemnitz).
The crystals from these localities are small and are rarely larger than 5mm. We need someone to tell us about the acanthites from this deposit.
This locality was formerly known as Joachimstal. The Vienna Museum is reported to have exceptional crystals of octahedra from Joachimstal. The largest crystal may be about 2.5 cm. Jáchymov is the type locality for real monoclinic acanthite as opposed to the isometric forms (cubes, octahedrons etc.) that are acanthite pseudomorphs after argentite. “Clusters of black crystals to 3 cm weighing several kg. This locality also produced long prismatic (monoclinic) crystals to about 5 mm. At nearby Medenec crystals larger than 5 cm were collected in 1970.”1
1. Jaroslav Hyrsl, personal communication 2003.
Formerly large crystals to 3 cm.1
1 Jaroslav Hyrsl, personal communication 2003.
Moldavia. A fluorite deposit in Moldavia also produce nice octahedrons to 1 cm.1
1. Jaroslav Hyrsl, personal communication 2003.
England, Cornwall, near Liskeard, Wheal Ludcott and Wheal Newton
Good acanthite specimens have been found at both these localities. The two specimens pictured here are in the British Museum of Natural History and may be the best in existence. I have never seen anything in quality close to them.
Colorado, Aspen and Leadville.
Acanthite crystals have been reported here but few specimens you see are going to be impressive. Colorado with its long history of silver mining undoubtedly produced some good ones but they almost all converted into silver coins. I have never seen a good acanthite specimen from these localities.
Colorado, Clear Creek Co., Silver Plume.
Dave Bunk of Denver, has a 7x10 cm specimen of crystallized acanthite with skeletal cubo-octahedrons up to 3 cm. He also has perhaps the best acanthite from this mine which is a miniature sized specimen with rounded cubes to about 12 mm. Though this is not a large specimen it is very appealing and to most collectors more desirable than the 7x10 cm specimen described above. Dave Bunk says he has seen about a dozen decent specimens from this locality.
Idaho, Elmore County, Atlanta District, Buffalo Mine.
A 4.8x 4 x 2.3 cm fairly well formed acanthite crystals from the Buffalo Mine is in the Collection of Jim Minette or Boron, California. The specimen is believed to have been collected in the 1880s.1
1 Minerals of Idaho, Lanny R. Ream, 1989, p.
The specimen pictured here in the Harvard collection from Butte is interesting because the acanthite crystals are growing in and on clear gypsum cleavages. Some of the best acanthite specimens from the USA occur at the Silver Bow mine at Butte. Perhaps the best specimen from this mine is in the Montana Tech collection at Butte and has acanthite crystals growing on green-brown siderite. Thanks to Jim McGlasson of Tucson for this information. Dave Bunk of Denver who specializes in silver specimens says he has never heard of a mine called the Silver Bow and that all the good acanthites he has heard of have come from Walkerville a suburb of Butte. Check the Butte issue of the Min Rec and talk with Terry Wallace about this.
Nevada, Storey County, Virginia City, Comstock Lode.
Large amounts of acanthite, thousands of tons, were found and certainly specimens with good crystals were encountered, but few of them appear to have been saved. An outstanding one is in the George Witters collection in Denver and other is a “pair of dice” in the Mackay School of Mines in Reno, Nevada.
George Witters has an octahedron of acanthite from??? that measures about 12 mm. So get his email address and ask him about it?
Utah, Park City.
This mine has produced some good specimens but they are rarely seen. Martin Zinn of Evergreen, Colorado has a fine specimen from this locality. The specimen is approximately 5x7 cm with fairly sharp cubic acanthite crystals up to 12 mm associated with small white (5 mm) calcite crystals and small silver wires poking out here and there on the specimen. Dave Bunk of Denver has a similar specimen measuring 6x10 cm. The acanthites are fairly sharp but not particularly lustrous.
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Edited 90 time(s). Last edit at 12/15/2015 08:26PM by Olav Revheim.
Rob Woodside December 28, 2008 07:25PMRayas may not be finished. Recently Great Panther Resources, a Canadian mining company, bought out the old Mining Cooperative and began development work at depth. They have encountered more rich veins and we have yet to see what specimens will be produced. La Serina, the sister mine to Reyas produced both lustrous small cubes of Argentite less than a cm and lustrous cm sized Acanthite prisms on white matrix on the same specimen showing the deposition temperature to be around 180 C.
Rock Currier December 29, 2008 01:27AMBob,
Thanks for the interesting tid bit about the Reyes mine. I have included it in the text about that mine and hope you will contribute more to Best Minerals when you are able. If a couple of thousand other mineral people step up and help with this project when it goes site wide I think you can see it will be a useful resource. I hope to shortly get my slide scanner set up and running so I can add some thousands of mineral images to Mindat and to hook them up to the species/locality articles I am generating here. I have been rather disappointed in the quality of the acanthite images (the quality of the specimens pictured) offered on Mindat and for that matter the overall quality of the specimens. I suspect that some of the high end dealers don't want to show what their really good stuff looks like because it will make it more difficult to sell their average material. I know I can add in most cases contribute images of better specimens that are generally shown on mindat.
If you have the time, though observing how much effort you are already putting in on mindat I can't imagine where you would find it, feel free to start one or more threads about minerals that have interested you have more than average knowledge of.
Crystals not pistols.
Rob Woodside December 29, 2008 03:43PMThanks Rock. I think this is an important, useful, and interesting project. When I first heard of it, I wondered where you would find the time. So far I've only corrected 3 typos. This generates an impressive "Last Edited by...", terrifying the author and leading others to think I might know something!!! I'll start a thread on Husky Polybasite and Stephanite when I can. Thank you for your considerable efforts on this.
Rock Currier December 31, 2008 08:21AMRob,
Thanks for your edits. I am not worried about the number of edits. I think I have about 50 edits on the Azurite thread alone. The more edits the better. I am not worried about managers editing things. We are always very restrained in editing things on miindat, and it is going to take a lot of editors/moderators to push the project the way it should be pushed. What I don't want is for just anyone to be able to go in and edit the articles that are being constructed and polished in the first posting on each thread. Do you know what level of permission is needed for someone to go in and edit a thread posting?
Crystals not pistols.
Rob Woodside December 31, 2008 07:53PMThe changes here are so fast paced and my hiatus has left me wondering about levels of accessibility. There is now a "helper" catagory at 2.5??? That would probably work for polishers or moderators of this project. Creating managers seems fairly loose. A manager proposes someone and posts it at the management board and when the consensus is positive, the person is welcomed with a surprise when they next login.
David Von Bargen December 31, 2008 08:50PMYou have to be a moderator to edit anything on the messageboard (unless it is your post). Right now that is just the managers or you have to be set up as a moderator for a forum. Probably could set up a group to be given permission to moderate this forum.
Rock Currier December 31, 2008 09:23PMOK, I understand. I think we may eventually need to set up such an authorization group to help with this project. I would love for the managers to jump in and help here, and some have already, but I think most of us already have our hands full just taking care of areas on the site in which they have in interest as well as talent. An authorized group of moderates for the Best Minerals forum I think may be the way to go, but we don't need it yet. Ill let you know if I need to get anyone authorize to be a moderator of the forum. Also if any of the managers know of anyone interested in working on the project that they think would be compatible with the group we should probably make them moderators as well. But for now I still have a huge pile of work to do and am still fiddling with the format, content and the welcome section in the sticky note.
Crystals not pistols.
Maurizio Dini March 17, 2009 09:18PMDear friends;
acanthite may also occur as acicular needles; such xls habit is not that uncommon as we always learned about the isometric habit of this marvellous mineral.
Here in Chile, there is at least 2 locality which has produced tiny acicular puffs or needles aggregates; maybe Rock can search for a type foto of that.
David Von Bargen March 17, 2009 10:43PMhttp://www.mindat.org/photosearch.php?frm_id=mls&cform_is_valid=1&minname=acanthite&cf_mls_page=1®ion=&text=acicular&otype=0&stype=0&phototype=M&mtype=0&sort=&submit_mls=Search
OK, I give up. We should have acicular acanthite represented in the article. I added an example from France and another from Italy.
Edited 1 time(s). Last edit at 03/18/2009 07:58AM by Rock Currier.
Martin Stevko April 27, 2009 08:24AMHello,
Some additional informations about acanthite from Banská Štiavnice in Slovakia:
This locality produced acanthite crystals up to 3 cm. Large crystals are usually rough. Superb examples of acanthite from this deposit
are displayed in Natural History Museum in Vienna. Acanthite is usually associated with quartz, pyrite and silver. Specimens from this
locality are today rare on the market.
Jáchymov is in the Czech Republic not in Slovakia!
Peter Haas April 27, 2009 09:56AMNotes:
(1) Fine acanthite was also found at Sainte-Marie-aux-Mines and at La Croix-aux-Mines, but decent specimens from these mining districts are exceedingly difficult to obtain.
(2) Quite often, acanthites from the Erzgebirge form rounded aggregates, which occasionally were sold as argentopyrite or even argyrodite (when yellowish). The silvery balls in this specimen may be acanthites too: http://www.mindat.org/photo-129487.html (not an uncommon association).
Edited 1 time(s). Last edit at 04/27/2009 09:57AM by Peter Haas.
Sebastian Möller April 27, 2009 05:57PMHello,
The biggest specimen from Freiberg mining district are abou 26 cm. It is an aggregate of cm-sized cubes (acanthite paramorph after argentite). Its part of the mineralogical collection at the TU Bergakademie Freiberg. I have seen it there, together with many others. I think it is from Segen Gottes Mine, Gersdorf near Freiberg.
The tales say that at the time of duke August der Starke (August the strong) in the early 18th century they had made coins directly from acanthite, the mineral has been such frequent at that time.
There have also been neat pseudomorphs of acanthite after silver wires and acanthite xls up to 6 cm formed like knife blades.
Jeffrey Fast May 26, 2009 03:46AMRock,
You mention stories of miners selling acanthite crystals for next to nothing thinking they were galenas. On my first trip to Guanajuato many years ago, I bought a lot of acanthites from an engineer who had a construction firm. He had been buying acanthite crystals for quite some time. Unfortunately, a few devious miners sold him some galenas as extra fine and extra large acanthites. It took a while, but the engineer eventually caught on and decided to get out of the hobby and go back to construction. I bought the remains of his collection and it included several galenas. I only paid for the acanthites!
Paul De Bondt May 26, 2009 11:45AMHi,
Yes Peter, you are right about Sainte Marie-aux-Mines.
I have a specimen of 289 gram with wire Silver on it. There where, according to Bari, few crystals observed.
The most common form are massive masses where one can see the inverse saddle cast form from the Ankerite pockets they " grew " in.
The silver wires completes the association.
By lack of time, I can not make pictures right now but I save all the messages concerning minerals I can add in numerous galleries, like Anatase, Arsenic etc... but I promised Harjo to help him also with his articles.
Take care and best regards.
Paul De Bondt June 08, 2009 12:15PMHi Rock, Peter and all,
I translated a little article about Acanthite from Sainte Marie-aux-Mines.
Here it is.
Acanthite, Sainte Marie-aux-Mines.
It used to be a very important Silver ore during the exploitation of the mines and have been found in nearly all the veins of the Neuenberg. ( veins discovered in 1549 )
It is usually associated with Pearcéite, Matildite and Native Silver.
The Saint Pierre mine, who exploited the Saint Guillaume vein, provided the best specimens.
Some rare crystals have been observed in the Saint Jacques vein.
According to old manuscripts, the mineral was quite frequent in the Saint Jean vein but only in small pieces.
According to old collection catalogues, many fine specimens where recovered and all specimens describes the same morphology.
They occurred always in a specific paragenesis, better known as the “ paragenèse a carbonates nobles “, constituted by Calcite, Dolomite and Ankerite in Quartz vugs. The imprints, seen on the surviving specimens, come from the Ankerite crystals.
Monnet ( around 1780 ), wrote.
In 1748, the miners found in an enlargement of a not specified vein, 3 feet wide and 5 feet long, 8 quintals of massive and pure Argentite. ( 1 quintal = 100 lbs )
It is only recently, in June 1981, that a fine specimen, a piece worth of the old findings, was found again. ( not specified but probably in a museum collection )
Almost 100 gram massive Argentite, typically with rhomb imprints with atop the Argentite, a very fine fibrous mass of Native Silver.
Unfortunately, no exact mine or vein is given.
In 1993, while reorganising partially the Sorbonne collection, another specimen, much better than the 1981 piece was found. It consist of 289 gram Acanthite, also mounted with Native Silver and bearing the typical rhomb imprints. The label states Sainte Marie-aux -Mines but here also, unfortunately, no exact locality is given. This is the best surviving witness of the fantastic finds and comes probably from the Saint Guillaume vein. The specimen bears a catalogue number and I have contacted the Sorbonne to consult the catalogue but received no answer yet from the actual curator of the collection.
Translated from the paper " Minéralogie des filons du Neuenberg à Sainte Marie-aux-Mines " from Hubert Bari, 1982 "
I hope this helps.
Take care and best regards.
Karl Volkman June 08, 2009 06:06PMRegarding the "Daybreak Mine" acanthite. I have serious doubts about the prominence of the specimen. In fact Leo 1960 ("Autunite from Mt. Spokane, Washington") reports that aside from "submicroscopic uraninite particles" Autunite is the only ore mineral present at the Daybreak.
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