Home PageMindat NewsThe Mindat ManualHistory of MindatCopyright StatusManagement TeamContact UsAdvertise on Mindat
Donate to MindatSponsor a PageSponsored PagesTop Available PagesMindat AdvertisersAdvertise on MindatThe Mindat Store
Minerals by PropertiesMinerals by ChemistryRandom MineralSearch by minIDLocalities Near MeSearch ArticlesSearch GlossaryMore Search Options
The Mindat ManualAdd a New PhotoRate PhotosLocality Edit ReportCoordinate Completion ReportAdd Glossary Item
StatisticsThe ElementsMember ListBooks & MagazinesMineral Shows & EventsThe Mindat DirectoryHow to Link to MindatDevice Settings
Photo SearchPhoto GalleriesNew Photos TodayNew Photos YesterdayMembers' Photo GalleriesPast Photo of the Day Gallery
Posted by Rock Currier
Rock Currier June 17, 2009 09:18PMThis 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, R. (2009) Colemanite. revision 1.0. Mindat Best Minerals Project, article "mesg-69-141984". Please be advised that the photos cannot be used without the consent of the copyright holder
Ca3O4(OH)3> · H2O
Colemanite has perhaps more different crystals forms than any other mineral than calcite. Here in the USA, probably the most commonly seen crystals forms are the little spiky bladed crystals from Boron, California, but if you want big blocky crystals you will probably try and get one from the Boraxo mine near Ryan in Death Valley ore some of the fine crystals from Turkey. A fine single crystal from Death Valley of about 15 cm is pictured below. This crystal is certainly not the largest found at this locality and the Handbook of Mineralogy indicates that crystals up to 30 cm have been found in Turkey.1 Colemanite, when heated will crack and pop as the water is driven out of its structure. It has pretty good cleavage and often has razor sharp edges. The old prospectors when testing for borate content would take a bit of the mineral, crush it to powder, put a few drops of acid on it and some alcohol and light it on fire. The flame would burn green. The specimens of Colemanite are often abundantly found. Most collectors rank them low in terms of desirability mostly because they are white and are often thought to be unstable because of their close association with sodium borate minerals like Borax and Kernite. Some Colemanite crystals are colored because of various inclusions and these will and do bring good prices. Though Colemanite is not unstable, sharp shiny crystals of Colemanite after being exposed to the polluted air of Los Angeles and undoubtedly other cities, do seem to loose some of their brilliance and luster. Crystals mined at the same time, but kept in the clean dry air of the desert near Boron, California retain most if not all of their brilliance. Many minerals are degraded over time and from that stand point and exceed Colemanite in degradation over time.
Colemanite has been one of the main ores that have been exploited for the production of borax and other borate compounds. Today Colemanite is still mined, but in very limited amounts for specialty products. Borax, a sodium borate provides almost all of the borates used today in industry. Most of this material comes from Turkey and from California, but Colemanite and Ulexite are still thought to have value and when and if the current deposits of sodium borates like borax are exhausted, Colemanite and Ulexite will return to being the main ores from which to produce borates for industry. At Boron, California, after the sedimentary sandy overburden has been removed, a layer rich in Colemanite and Ulexite is encountered and this material is set aside in its own separate dumps for future use. I suspect that they do the same in Turkey and I hope that someone will come forward and tell us about those deposits.
1. Handbook of Mineralogy, Anthony, Bideaix, Bladh & Nichols, Vol.V, p.158.
There many deposits of borates in the altiplano near Salta. One of these is a good sized open pit mine where borax is mined. They also produce Colemanite specimens, but not many have been saved for the collector community. We need someone to tell us about this locality and the specimens from it.
Zanjan Province, Dandy District, Gharah Gol Boron Mine
The specimens above are of low quality and the locality undoubtedly produced much better specimens. We need someone to tell us about this locality and its specimens.
Aegean Region, Kütahya Province
By far the largest deposits of borates yet discovered are in Turkey. Reserves are estimated to be in the billion ton range. Some estimates are that at least one mine has reserves at least ten times that of the big USA deposit at Boron, California. Years ago I was able to buy boxes of
Colemanite crystals of about 50 pounds each from a firm in NY City. and am sure that if there was a sufficient market for such things, that large quantities of these specimens could still be produced. But I don't really know much about the borate deposits of Turkey and hope that someone reading this who does, will step forward and tell us more about them.
We need someone to tell us about this deposit and its specimens.
Marmara Region, Balikesir Province
We need someone to tell us about this locality and it specimens.
Marmara Region, Balikesir Province, Bigadiç
We need someone to tell us about this locality and its specimens.
Balikesir Province, Faras, Sultancayin, Kurtpinari mine
Most Colemanite specimens are sold for modest prices but these root beer colored specimens brought surprisingly high prices. We need someone to tell us about this deposit and the specimens from it.
California, Inyo Co., Boraxo Mine (Kern Borate; Boraxo Deposit; Boraxo No. 1 and No. 2; Clara Claim; Thompson Mine; Tenneco Mine)
This is/was, in the overall scheme of things a small deposit of borates with Colemanite by far the main borate mineral found. The mine sat down in the flat area below the little mining camp of Ryan and was first operated as an underground mine that produced few specimens. The reason for the small production of specimens is that the mining process destroyed most of the specimens and to the mining company it was not worth the time or trouble to collect and market them. The underground portion of the mine did produce however most of the fine Hydroboracite specimens that have made their way to the collector market. Eventually the deposit was mined by open pit and this is when the majority of the fine big Colemanite specimens from this locality were collected. Some were floater plates of shiny blocky white crystals approaching two feet across. Hundreds of specimens were collected before the mine closed. On occasion the open pit was opened to amateur collectors and they hauled away many good specimens. That was more than 20 years ago and the specimens, like most of the specimens found seem to vanish and become hard to get.
California, Inyo Co., Death Valley, Furnace Creek District
The main road into Death valley from Death Valley Junction runs through this district. From this road you can take the little side road that runs through 20 Mule Team Canyon and if you know what you are looking for you can spot several of the old workings. In the gullies and canyons of the area are many small mines and prospect holes and tunnels, many of which produced Colemanite crystals of one kind or another. The specimen pictures above was collected from a short exploration tunnel in the district, but after so many years I doubt that I could even find the place again. It is also possible that natural erosional forces have completely caved the entrance to the tunnel which was a bit of a crawl when I found it years ago. There are a fair number of private mining claims inside Death Valley National Monument and yeas ago, they were all abandoned and you could wander around and collect to your hearts content, very unlike the situation today.
California, Inyo Co., Death Valley, Furnace Creek District, Black Mts, Gower Gulch, Gower Gulch Mine
A little hole in the wall place. Probably more correctly called a prospect rather than a mine. Sometimes you can find Colemanite crystals weathering out of banks and outcrops in the area. This specimen is an old timer I found in the collection of Yale University that almost certainly dates from the late 19th century and was undoubtedly taken from an outcrop. I just had to respect such a venerable old specimens and get a picture of it. Only a mother could love such a specimen.
California, Inyo Co., Death Valley, Furnace Creek District, Black Mts, Mount Blanco mine
The Mount Blanco mine is really more of a prospect than a mine. It consists of one short tunnel with two little side tunnels which by this time must be completely filled with natural breakdown of the tunnel ceilings or rubbish rock left by collectors digging for specimens. Almost all the Colemanite in the mine is of drusy material like the one pictures above. The mine did produce probably the finest specimens of Meyerhofferite pseudomorphs after Inyoite hat have been found to date. The specimen pictured above is nearly unique in that it shows the drusy Colemanite together with a pseudomorph. Usually the pseudomorphs are not found with Colemanite. The mine also has produced some fine specimens of primary Meyerhofferite crystals that have an almost reticulated look and some of those were associated with the typical drusy Colemanite.
California, Inyo Co., Death Valley, Furnace Creek District, Corkscrew Canyon, Corkscrew mine
The Corkscrew mine is a bit more of a proper mine but still a rather small one. It has a number of stopes from which Colemanite, by far the main ore, has been removed. The mine is like a giant jewel box and a swiss cheese with glittering pockets of drusy Colemanite everywhere you look, some of which are large enough to crawl into. For years you could go there and haul away as much drusy Colemanite as you could carry out of the place. The problem was that when you got them home, what could you do with them? They were almost impossible to sell and then only at very cheap prices, and it did cost money for gas to drive all the way up to the mine. Today the mine is locked up tight and the road to it closed. Its probably better that way because if it had remained open, someone would have surly have killed themselves in the mine and caved in the workings. At some future date, if the claim ever reverts to the government, it could be opened as wonderful tourist attraction. The mine is the type locality for Nobleite and may have produced the best specimens of that species as well. It has also produced some respectable specimens of acicular Ulexite on Colemanite, but they are so rare as to be almost not worth mentioning. Many of the specimens from the mine are colored tan or black which is said to be Todorokite included in the structure of the Colemanite. One of the more desirable kinds of Colemanites that the mine has produced are Colemanite pseudomorphs after Inyoite. Several of them are pictured above.
California, Inyo Co., Death Valley, Ryan, Widow No. 7 Mine (Old Widow)
The Widow mine is just one of the mines that was operated near the little mining camp at Ryan. US Borax owns the property and keeps a full time watchman at the camp. The mines at Ryan represent a seizable deposit of borates and the company wants to hang on to them against future need. These are real mines and have produced thousand of tons of Colemanite which was the main ore produced by the mines there. All of the mines have produced specimens of Colemanite, but since the mines are closed to collectors and the collecting of specimens is not profitable to US Borax, few specimens from these mines are available to collectors, though they certainly have the potential to produce many good specimens. For the most part, the crystals are small like the specimen shown above. The widow mine is he only underground borate mine I know of that has used square set timbering to mine borates. The stuff was obviously worth a lot more formerly than it is now. Initially the deposits that produced borates were from surface lake deposits of Ulexite where the ore was just skimmed off the surface of the ground. When the Colemanite deposits at Ryan were discovered, mining of these superficial evaporate deposits stopped and the mining of Colemanite at Ryan took over. The company even went so far as to put in a narrow gage railway from Death Valley Junction to the mines. Part of the old narrow gage track still connects some of the mines to the camp and they have in storage the old little locomotive that was used to pull the little train. When the big deposit of Borax was discovered at Boron was discovered and opened up, the mining at Ryan was stopped and the mines and camp put mostly in moth balls.
California, Inyo Co., Gerstley Mine (Gerstley I; Gerstley II; Gerstley Pit; Kern Company Land Company)
A little open pit mine that is mined from time to time for Colemanite. It has produced a few decent specimens but nothing to shout about.
California, Inyo Co., Death Valley Junction, Lila C Mine (Leila See; Lilac)
The Lila C mine is out in the flat, not far from Death Valley Junction and at one time was a pretty big producer of Colemanite. The crystals from the mine were not very notable as you can see from the specimen pictured above.
California, Kern Co., Kramer District, Boron, U.S. Borax Open Pit Mine
The great majority of the Colemanite specimens from Boron feature small cm size sharp spiky bladed white crystals growing on massive colemanite. There were very few Colemanite specimens available from the underground workings, but when the deposit was open pitted huge quantities became available. In the early days it was possible to even collect in the open pit itself, and after that was closed to collectors, it was still possible for a few years to go and collect on the dumps to your hearts content. I was never afforded free access to the open pit, but I was able for a while to collect freely on the dumps. You just had to be careful that while collecting that a 150 ton haul truck would not dump its load down on top of you while your were collecting on the lower slopes of the dump. Some fabulous specimens were collected from the dump and since colemanite was the most common thing you could collect on the dump you were always looking for the less common minerals. The great Tunellite specimens were mostly collected from one of the borate dumps at boron. The Colemanite crystals were razor sharp and sometimes when swinging a sledge you would find the handle getting slippery from blood from cuts that were made by crystals that were so sharp you didn't even know you were cut. Sometimes this lead to the amusing situation where you didn't realize you were bleeding and got excited when you found a colemanite specimen with Realgar on it only to realize later when you looked at it carefully that the red was your blood and not Realgar which was not unusual in the deposit. The Realgar only rarely occurred in well formed crystals and then only as micro crystals.
You could collect tons of colemanite specimens if you wanted them, but fine ones were always in short supply. I soon gave up trying to dig much on the dumps because I found that you could much more easily buy fine specimens from the miners who worked in the open pit than you could get by digging. In the early days there was a lot of calcite found associated with the colemanite and now that association is uncommon. The tan or golden calcites made for striking combination specimens, many of which are pictured above. A one inch crystal was uncommon though once in a while crystals of two or three inches were found. Perhaps the grail for devotees of the locality were the red and yellow Colemanite specimens. The yellow color may be caused by Pararealgar and the red was said to be caused by Realgar but since long exposure to light did not seem to discolor the colemanite, I have my doubts. The big red and yellow Colemanites pictured above may be the best of their kind.
The deposit at Boron was discovered by a local who was digging a well. There are no outcrops in this flat part of the Mojave desert that would lead one to think there might be a huge deposit of borates below ground. Eventually drilling and shafts indicated the presence of huge amounts of borates and better yet, a great deal of sodium borate in the form of Borax. This was incredibly attractive to the mining company because it was so easy to dig and process. All you had to do to purify it was to dissolve it in water and then recrystallize it. This deposit effectively put all the other borate mines out of business unless they too could mine borax. The stuff could be mined cheaply enough that for the first time it could be offered to the retail market as a water softener. The borax (sodium borate) when dissolved in water would then combine with the calcium and magnesium in the water and in effect make it soft and allow the soap in the wash to work better. As the mine developed it became the largest underground mine in California with more than 200 miles of stopes and tunnels. The borax was mined with continuous miners very much like coal is mined in many mines. In the 50s it was decided to open pit the deposit and in the late 50s saw the first production from the open pit mine. The three main shafts that accessed the deposit were the from east to west the Baker, Jenifer and the West Baker. Few specimens of Colemanite were produced by these mines because only the top most layer of the deposit contained Colemanite and Ulexite and the three shafts that accessed the deposit passed through this layer to access the sodium borates which lay below them. Almost all of the mining was done below the Colemanite and Ulexite layer. But when the sandy overburden was removed and mining striped off the Colemanite and Ulexite layer countless specimens of Colemanite were encountered, the vast majority of them were promptly hauled out onto the dumps that were set aside for the long term storage of this ore that might someday become valuable.
ColemaniteUSACalifornia, San Bernardino Co., Calico Mts, Calico District, Calico-Daggett Borate area, Pacific Mine (Borate; Borate Colemanite Mines; Calico; Old Borate)
The mines here were real mines and thousands of tons of borates, mostly in the form of Colemanite were taken out and sold. The mines produced good crystals, but few were saved. I think I have seen less than a half dozen in the 50 years I have been interested in borates.The crystals are blocky and white and the largest I have seen is perhaps two to three centimeters in diameter.
Click here to view Best Minerals C and here for Best Minerals A to Z and here for Fast Navigation of completed Best Minerals articles.
Crystals not pistols.
Edited 18 time(s). Last edit at 12/22/2015 06:43AM by Olav Revheim.
Th. Krassmann October 02, 2009 09:36PMHello from Germany
Regarding the "root beer" colemanites from Turkey : They originate from the Kestelek Mine near Mustafakemalpascha, western Anatolia. We were lucky to find those specimen on a fieldtrip back in 2005. Interesting aspect about these specimen are, that the "root beer" colour is coupled with twinning...if you find untwinned crystals, they are of much paler colour or even colourless ! And they have a nice fluorescence as well.
Regards from Bavaria
Rock Currier October 25, 2009 03:54AMPavel, Thank you for the image. Its better than nothing. Have you any idea how many Colemenite specimens were collected and distributed from Inder? Were any of them shiny, or did they mostly have the surface texture of your specimen? Not the biggest and best from the locality? Sounds like most of the specimens in my collection.
Crystals not pistols.
Pavel Kartashov October 25, 2009 02:13PMI am think some tens tons of colemanite specimens were extracted, because in any personal collection or collections of different museums, institutes, univercities, shcools and exibitions on all territory of former USSR including colemanite, it is represented by Inder material.
Besides that, many thousands tons of colemanite were used as B ore.
Of course shiny crystals and druses of them and also radial concretions covered by crystal terminations are known from Inder mines.
Edited 1 time(s). Last edit at 10/25/2009 03:39PM by Pavel Kartashov.
Ron Crouse October 27, 2009 05:12PMI worked at the Boron mine for 16 months several years ago as a geotechnical consultant. I came to the conclusion that the best colemanite crystals were formed at the intersection of high angle faults with ulexite beds. Over time, the meteoric water would begin to convert the ulexite, and there would be a reduction in volume, which resulted in open cavities for formation of nice colemanite crystals. I actually found two very large crystals on the order of 4 inches in size, which I gave to the mine geologist, Joe Siefke. I don´t know what he did with them.
Bob Griffis June 25, 2011 04:14PMRock,
The Billie Mine also produced lots of fine specimens of glassy, blocky crystals of Colemanite, sometimes associated with Veatchite and Celestite. I'm sure you have a few floating around. I have a pretty good systematic suite (by location in the mine) and as I dig them out, I start posting photos. I knew 3 of the geologists at the mine, including Walt Lombardo, so I had plenty of access to specimens, and collected a 1 meter pocket once with 6 to 8 cm crystals.
Sorry, only registered users may post in this forum.
Mindat.org is an outreach project of the Hudson Institute of Mineralogy, a 501(c)(3) not-for-profit organization.
Copyright © mindat.org and the Hudson Institute of Mineralogy 1993-2017, except where stated. Mindat.org relies on the contributions of thousands of members and supporters.
Copyright © mindat.org and the Hudson Institute of Mineralogy 1993-2017, except where stated. Mindat.org relies on the contributions of thousands of members and supporters.