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Edenite series

Posted by Olav Revheim  
Edenite series
March 07, 2011 06:22PM
no    
First draft




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Can you help make this a better article? What good localities have we missed? Can you supply pictures of better specimens than those we show here? Can you give us more and better information about the specimens from these localities? Can you supply better geological or historical information on these localities?

The Edenite series minerals are minerals in the Amphibole group, see Amphibole Group main article for an overview of the group. The series contains the following minerals:

Edenite
Na Ca2Mg5(Si7Al)O22OH2

Ferroedenite
Na Ca2Fe5(Si7Al)O22OH2

Fluoro-edenite
Na Ca2Mg5(Si7Al)O22(F,OH)2

Parvo-mangano-edenite
Na(CaMn2+)Mg5(Si7Al)O22(F,OH)2

Chloropotassic Ferroedenite- IMA status Named
K Ca2Fe5(Si7Al)O22(Cl,OH)2

Fluoroedenite 0,92mm crystals from Biancavilla Mt Calvario, Italy © Chinellato Matteo


Edenite is one of the classic amphibole minerals, first described from Edenville, New York USA in 1839. The Edenville location is one of the many great amphibole localities in New York and Ontario in the marbles and contact rocks formed during the Grenville orogeny. Large and well formed edenites are found here, although many of the classic edenites has proven to be pargasite or other amphiboles rather than an edenite- series mineral. Even at the type locality the occurance of edenite has been questioned ( Handbook of mineralogy).

The edenite molecule (magnesium end member) is unstable and pure edenite has not been found in nature, and it has even been impossible to make synthetic . (Oberti et all. 2006). It has been found that Fe and F stabilizes the edenite molecule and therefore will any edenite found in nature always contain some Fe and/or F and ferroedenite and fluoroedenite are more stable and more common than edenite.

The edenite series minerals are primarily found in marbles and calc-silicate/skarn rocks and as microcrystals in volcanic rocks. It can also be found in the alkali rocks in Russia and Norway.

The largest crystals are those of the marbles of New York, US and Ontario Canada, where well formed crystals and crystal clusters can be freed from marble. The not so well formed crystals in the alkalipegmatites at the Langesundfjord may also exceed 10cm, but as they are not as attractive as the American crystals.

Edenite-series minerals from Mogok in Burma can be gem quality, and is sometimes faceted. These gem quality crystals is probably the most attractive for collectors due to their color and gemminess.

Attractive edenite-series micro-crystals can be found in relatively recent lava flows at many locations.

Edenite-series minerals do not form visually appealing display specimens and are therefore not often displayed in museums or other prominent collections, except for presentation of local or regional minerals. The New York State Museum’s web presentation of amphibole minerals found in New York is a very good example.


Edenite
Burma(Myanmar)
Mandalay Division, Sagaing District, Mogok,

Edenite 3,5 cm ©


The identification of this specimen is confirmed by X-ray diffraction and chemical analysis (rruff.info).

The Mogok Tract of Myanmar is known as one of the most famous locations for gem rubies, sapphires and spinels. The area is also host for more obscure gem minerals, such as edenite and fluoroedenite, found during occational mining for mineral specimensl.

The edenite appears to be found in the same geological environment as the rubies and other gems. The Mogok tract is predominantly a marble belt formed from Proterozoic sediments (>750 MYa) metamorphosed by collision with a Gondwana fragment (Burma Block) in Cretaceous time (~150 MYa) and later with the Indian block in Eocene time (~50 MYa).

The gem and collector minerals are formed in the marble itself during metamorphosis, or by metasomatic and pneumalytic processes in the contact zone between the marble and the surrounding rock. The marble is in contact with a wide range of igneous rocks, both granitic, mafic and alkali rocks of various ages and compositions. This gives an extensive mineral suite, of which edenite is one of the minerals.

Mogok edenite is not easily available on the market, and it is difficult to say how good the crystals get. Their qualiy is outstanding for an amphibole, and faceted gems exceeding 5 carats has been made. It is difficult to estimate the value of edenite specimens from Mogok, as the gem value of the specimen may come into play. There should be no doubt that a gemmy, well formed edenite crystal would be considered a “high end” amphibole.


Fluoroedenite
Burma (Myanmar)
Mandalay Division, Sagaing District, Pein Pyit (Painpyit), Pyant Gyi mine (Pyan Gyi)

Fluoroedenite 2,5x2 cm© Pavel M. Kartashov


The Pyant Gyi mine was originally opened to extract pinkish red spinels and pink scapolite from alluvial sediments. Later the mining operations extended into solid rock and today several small mines. High quality specimens of the rare mineral johachidolite has been found in a pegmatite in one of the mines together with other attractive mineral specimens . As a result, specimen mining both from the pegmatites and the marble/skarn has become interesting, and even some fluoroedenite has been secured, probably from the marble.

As the caption of the photo says, this particular specimen is of intermediate composition between edenite, fluoroedenite and pargasite, and falls barely within the fluoroedenite composition. The two Burmese entries illustrates the impossibility of naming amphiboles from appearance, as these two identically looking specimens from the “same” location are different minerals


Edenite
Canada
Ontario, Haliburton Co., Monmouth Township

Edenite 4,5 cm © John Sobolewksi


Haliburton County is a highly metamorphosed terrane comprising granitic,basic, ultramafic and feldspathoidal intrusives and a sedimentary sequence of marbles, calc-silicate gneisses, quartzites and intermediate paragneisses. Interesting mineralizations are found in the contact zones between the marbles and various intrusives. The amphiboles was originally described as tremolites, actinolites and hornblende. The new nomenclature and modern analytical techniques has revealed several different amphibole species in the calcic subgroup, edenite being one of them. The amphiboles previously identified as hornblende are very difficult to identify, and chemical and structural analysis will be necessary to distinguish them. Several species may also be present at the same location. ( ref F.C. Hawthorne and R. Oberti et al: "Short range order in amphiboles from the Bear Lake Diggings. Ontario, Canada" )

Well formed crystals up to 30 cm has been described.


Edenite
Canada
Ontario, Haliburton Co., Monmouth Township ,Wilberforce

Edenite some 12 cm across© 2007 Peter Cristofono


Also from this location, large well formed edenite crystals can be found in the conatct between marble and intrusives.


Edenite
Canada
Ontario, Hastings Co., Faraday Township, Town of Bancroft

Edenite 2,2 cm© Rob Lavinsky


This specimen should probably be attributed to the general Bancroft area, rather than from the Town of Bancroft itself, see Link to Mindat forum.


Edenite
Canada
Ontario, Renfrew Co., Renfrew

Edenite 5mm©


Apparently, edenite crystals can be found in the contact zone between marble and intrusives also here. Edenite from Renfrew is not listed in Mindat, but the identification of the pictured specimen is confirmed by RRUFF.


Fluoroedenite
France
Auvergne , Puy-de-Dôme , Monts-Dore massif, Chastreix , Roc de Courlande

Fluoroedenite FOV 3mm© JM. Johannet
Fluoroedenite FOV 2,4mm© Robert Vernet


The fluoroedenite has been found as beautiful microcrystals in vugs in mafic enclaves in trachy-andesite dome-flow, , coming from Mont Redon. Good outcrops on the road to Chastreix-Sancy ski station, just below the Roc de Courlande.

The Monts-Dore Massif has had active vulcanism since 15 mill. years ago. The fluoroedenite from this and the next location is found in the last lava flows ( 450.000 - 200.000 years ago) in reølatively short ( 500m-3km) and thick (10-20m) lava flows.


Fluoroedenite
France
Auvergne , Puy-de-Dôme , Rochefort-Montagne, Le Mont-Dore Massif, Ravin des Chèvres (Rivaux Grands)

Fluoroedenite FOV 2 mm© SMS 2009
Fluoroedenite FOV 2,7mm© SMS 2009



Fluoroedenite FOV 2,7mm© Robert Vernet
Fluoroedenite FOV 3mm© Robert Vernet


Fluoroedenite has been found as beautiful microcrystals in vuggy mafic enclaves contained in trachytic ("sancyite" ) matrix. Enclaves have been collected in the streambed of the "Ravin des Chèvres" ravine, and come from the cliffs below Puy de Cliergue.

Locality first described by A. Lacroix (Minéralogie de la France) under the name Rivaux Grands, but Ravin des Chèvres is a more accurate name.


Fluoroedenite
Italy
Novella Quarry (Cava Novella), Ercolano, Campania, Naples Province, Somma-Vesuvius Complex , Monte Somma

Fluoroedenite FOV 4mm© Enrico Bonacina

Fluoroedenite FOV 5,5mm© D. Preite - E.B.
Fluoroedenite FOV 7,72mm© Chinellato Matteo


Monte Somma is an igneous, arc-shaped mountain that represents the remnants of an older volcanic cone destroyed in a cataclysmic event in 79 d.c. (when Pompei and Ercolano were destroyed and where Plinius the Old died trying to study the eruption). Mt. Vesuvius is the current cone over the vent.

The age of the oldest products in outcrop is about 25,000 years.The latest round of activity seems to have ended with the eruption of March 1944. This eruption was the beginning of a resting phase characterized by modest signs of seismic activity and fumarole (Arno et al., 1987).
More than 230 species has been found in this area, and is one of the most interesting places in Europe. There are in principle four different mineral forming environments, each with a different mineral assemblage;
I. Minerals that are found in the ejected limestone blocks of Monte Somma.2
II. Pneumatolytic minerals formed in cavities of leucotephrites and conglomeratic blocks ejected by Monte Somma and Vesuvius, or coating the walls of ancient lavas.
III. Fumarolic products.
IV. Minerals that occur as rock constituents of Vesuvius and Monte Somma.
Amphibole minerals can be found in all of these mineral forming environments

Collecting in the Somma Vesuvius comples has been banned since 1995, but Fluoroedenite has been found and identified from old samples. Fluoroedenite occurs widely in miarolic cavities in lava fragments. The crystals up to a mm long is amber in color, have monoclinic prismatic habitus acicular and are longitudinally striated. The mineral is typically associated with hematite.

The occurance is confirmed in Russo, M., Della Ventura, G., Campostrini, I. & Preite, D. (2009). Nuove specie minerali al Monte Somma:I. Fluoro-edenite. MICRO (notizie mineralogiche), 2/2009, 173-174.


Fluoroedenite
Italy
Sicily, Catania Province, Etna Volcanic Complex, Biancavilla Mt Calvario

Fluoroedenite 0,92mm crystals© Chinellato Matteo


Fluoroedenite FOV 15 mm© Antonio Borrelli
Fluoroedenite FOV 4 mm© ELmar Lackner


Fluoroedenite FOV ~3 mm© Frank de Wit
Fluoroedenite 1,06 mm crystal© Chinellato Matteo


This is the type locality for fluoroedenite, but it was a rather unpleasant situation that led to its discovery. Italian health authorities had found higher than normal frequency of malignant pleural mesothelioma in the Biancavilla area. This was found to be caused by the presence of asbestiform amphiboles in local rocks used for building material. It was originally believed that these amphiboles where tremolite or actinolite, but closer investigations revealed a hitherto unknown mineral, fluoroedenite.

Fluoroedenite are found as fibrous masses in cavities in the rock, but also as mm sized prismatic or agicular crystals of an intense yellow color. The host rock is a relatively recent benmoretic lava, and it is believed that fluoroedenite is formed by late –stage hydrothermal fluids


Edenite
Ferroedenite
New Zealand
North Island, Bay of Plenty , Rotorua, Mt. Ngongotaha, Hendersons Quarry

Edenite FOV 2mm© Judy Rowe
Edenite FOV 5,5mm©
Edenite FOV 9mm©


Ferroedenite 3mm crystal© Leon Hupperichs
Ferroedenite FOV 3mm© Judy Rowe



Ferroedenite 0,61mm crystal© Chinellato Matteo


This location is a quarry that produces road gravel for the local market. It is located in a rhyolittic lavaflow from Mount Ngongotaha. Mount Ngongotaha with it’s 757m above sealevel is the largest of several rhyolitic dome vulcanoes in the Rotura volcanic centre. Although located in an active volcanic zone, the Mount Ngongotaha has been dormant for more then 150.000 years.
The edenite is formed by late hydrothermal activity and micro-crystals (mm sized) can frequently be found in cavities in the rhyolite together with numerous other minerals.
Edenite and fluoroedenite is confirmed by SEM-EDS.


Ferroedenite
Norway
Vestfold, Larvik, Langesundsfjorden, Barkevik area, Skutesundskjær (Skudesundskjær)

Ferroedenite 6.45cm x 4.75cm x 2.7cm
specimen
© Jasun McAvoy


Ferroedenite can be found as a rock forming mineral throughout large parts the Langesundfiord larvikite) district. The larvikite rock ( for the most part a alkali-monzonite) covers an area of more than 1000 sq. Km, and it is worked extensivly as a decoration stone. The larvikite hosts a large number of alkali pegmatites that carry a wide variety of minerals, some of them very rare.

.According to Larsen et.al. 2010, the amphibole from the eastern part of the Langesundfjord and Tvedalen are generally ferro-edenite. This includes most of the specimens labeled by the old, now discredited name “barkevikite”. Numerous other amphiboles may also be found in the various rocks in the Larvik pluton.

Ferroedenite are abundant in this area, and in pegmatites they may reach a size of more than 1 dm. They are normally embedded in feldspar and normally crude and not very well formed.


Fluoroedenite
Russia
Northern Region, Murmanskaja Oblast', Kola Peninsula , Mt., Khibiny Massif , Yum'echorr (Yumjechorr)

Fluoroedenite FOV 12x10 mm© Pavel M. Kartashov


Yum'echorr is part of the alkaline Khibiny pluton. This is an nepheline-syenite ( foyalite) intrusion some 30km in diameter, which consists of numerous varieties of nepheline syenite arranged in concentric circles/arcs. The intrusion is horseshoe shaped with the opening towards the east.Minerals occure in 4 different environments,
  1. the nepheline syenite itself
  2. in xenholites (rock fragments) from the “ceiling” of the pluton
  3. in metasomaticrocks on the borderline between the nepheline syenite and the surrounding gneiss
  4. in hydrothermal zones.

This variety of different mineral forming environment has created at least 25(!) different amphibole species, fluoroedenite being one of them. Edenite-series amphiboles can be found in one of the minor nepheline syenite arcs as crystals up to 3cm in size.


Edenite
Fluoroedenite
USA
Franklin, Franklin Mining District, Sussex Co., New Jersey, USA
Edenite 4,8 cm tall© Cindy Hasler


Edenite occurs in the contact zones between the Franklin marble and the surrounding rocks metamorphosed in the Grenville oregony. Edenite is not found in connection with the ore deposits but it is widely disseminated in the Franklin limestone, especially near pegmatitic contacts and crystals up to 5 in. are reported.

There are other amphiboles present in this area, and most of the amphibole specimens named edenite are in fact pargasite or magnesiohornblende, (ref Pete J. Dunn franklin-sterlinghill.com) with pargasite as the most frequently occurring amphibole. Also fluoro-edenite are identified from the Franklin marble (ref: MINERAL SYSTEMATICS AND FLUORINE DISTRIBUTION IN THE AMPHIBOLES FROM TWO GRENVILLE MARBLE BODIES IN NEW YORK STATE LUPULESCU, Marian V.)


Edenite
USA
New York, Orange Co., Town of Warwick, Edenville,

Edenite 4x6cm tall© Arliguie M


Kearns (1977) says that this locality, his loc. 29, is also the probable type locality of edenite. Brown amphibole from this locality is near the ideal composition of edenite, and large well formed crystals are known.

It should be noted that the Handbook of Mineralogy questions the identification of edenite from here: “Name: For the locality at Edenville, New York, USA, although it is not certain to occur there.”

The minerals of the Amity-Edenville area occur almost exclusively in the Franklin Marble, a mid Protorozoic, granulite facies, calcite-rich metacarbonate. The Franklin Marble contains numerous horizons, often seen as isolated, elongated lenses but sometimes distributed in continuous trends.


Parvomanganoedenite
USA
New York, St Lawrence Co. , Fowler , Arnold Mine

Parvomanganoedenite, FOV 1cm © Caltech


Parvomanganoedenite occur intergrown with Parvomanganotremolite as 0,2-0,5mm grains in a manganiferous pod in the Grenville marble of the Arnold open pit, The manganiferous pod consists of stratifed rocks in
which layers 0.5 to 3.5 mm thick, containing mostly polycrystalline braunite, alternate with pale pinkish-brown layers composed mostly of calciferous Mn-rich amphibole with minor garnet


Fluoroedenite
USA
Oregon, Douglas Co., Lemolo Lake Quarry

Fluoroedenite © DM 01/08


This location lies in the same area as the location described below, and I assume that the geology and occurance is similar to the Summit Rock.


Fluoroedenite
USA
Oregon, Klamath Co , Summit Rock

Fluoroedenite FOV 12x10 mm© 2008, JGW


Summit Rock is a small andesitic plug dome in the High Cascade Range near Diamond Lake, Oregon. The upper 30 m of the interior of the plug were exposed in 1961 when it was quarried for crushed rock. Crystallized minerals are found in cavities in the upper part of the dome where it has formed form from volatile phases in the later stage of the cooling of the magma. Lots of rock still remains and micro collectors may still find nice material.

Fluoro-edenite has been identified by microprobe. Originally this material was called hornblende, then magnesio-hornblende before the similarity of this location to European occurrences was noted and closer investigations carried out. The mineral has almost an identical golden brown color to that of the more frequently found enstatite, so it does not easily stand out. Crystals may be long thin needles or short stubby prisms, but the defining feature is that the prisms tend to have six sides, and the termination is very blunt and flat, a (I0Ī) face predominating at a very slight angle from being straight across. The typical crystal size is about 1,5mm


Click here to view Best Minerals E , and here for Best Minerals A to Z and here for Fast Navigation for finished Best Minerals articles.



Edited 23 time(s). Last edit at 03/26/2012 10:52AM by Rock Currier.
avatar Re: Edenite series
March 07, 2011 06:27PM
us    
Edenite
USA
New York, Orange Co., Town of Warwick, Edenville,

Photo is from Franklin
Re: Edenite series
March 07, 2011 07:21PM
no    
Thanks David,

Cut & paste error. :)

Olav
avatar Re: Edenite series
March 07, 2011 09:22PM
Olav, You are getting the hang of it. Do this experiment and watch what happens. In the edit mode go to your New Zeland entry and at the end of the code string for the second image, put a single period (.).

Can you make some comments about how much of this stuff there is? Which localities produce the best specimens? Has it historically been called by other mineral names?

Rock Currier
Crystals not pistols.
avatar Re: Edenite series
May 16, 2011 11:26AM
Olav,

Thats a really good effort. I wish I knew enough about these minerals to make meaningful suggestions. You might tweak the size of your images a bit to make them look a little better. If for example you would like to put a little space between the second and third small images in the micros from New Zeland, just put a . (period) after the second one.

[ pic id=63097 width=221 float=right] Edenite FOV 5,5mm[/pic]

[ pic id=63097 width=221 float=right] Edenite FOV 5,5mm[/pic]. like this.

You can make this space smaller or larger by selecting the period and then changing the font size by using the tool bar above the edit box. The t/T button.

Rock Currier
Crystals not pistols.
Re: Edenite series
May 17, 2011 06:29AM
message erased



Edited 1 time(s). Last edit at 06/07/2011 06:38AM by Yanick Beaudet.
avatar Re: Edenite series
May 17, 2011 06:40AM
Yanick,
I do not understand what you want. You will have to explain yourself more clearly. Your English is very bad.

Rock Currier
Crystals not pistols.
Re: Edenite series
May 17, 2011 07:13AM
message erased



Edited 1 time(s). Last edit at 07/19/2012 12:34AM by Yanick Beaudet.
avatar Re: Edenite series
May 17, 2011 08:39AM
Yanick,
Here in the Best Minerals section of the Message board, unless you specify otherwise, you are addressing the person who wrote the particular article in the thread you are in. In this case it is Olav Revheim or perhaps myself, Rock Currier. I do not think either of us are looking to make teeshirts with mineral pictures on them, though the image leading into this article is certainly juicy enough to qualify if that is what we wanted to do. If you would like to know the purpose of Best Minerals and what we are trying to do click on this link: Welcome to the Best Minerals Forum.

Each person here on mindat that contributes to the site does so on a volunteer basis so each of us work here for various reasons. I am what is called a manager and Olav is almost one. There are currently 36 managers here on mindat, so when you leave a post like the one above, you should realize that your are addressing not some ultimate manager who says yes and no to all things on Mindat but to the mindat community at large unless you are replying to a particular thread posting or specify the person you are speaking to.

I think Jolyon Ralph, the founder of Mindat, was considering putting one or more images on teeshirts to promote Mindat. If you wanted to petition for a particular image to be placed on a Mindat teeshirt you should address a message to him in the General forum. The image is not a public domain image, and Chinellato Matteo holds the copyright on the image and he would have to be asked first if he would give permission to use the image for such a purpose. If your petition does not bear fruit with Jolyon, you might consider contacting Chinellato Matteo for permission to use the image and find someone to put it on a teeshirt for you. It is indeed a wonderful photo.

Rock Currier
Crystals not pistols.
Re: Edenite series
May 17, 2011 10:06AM
message erased



Edited 1 time(s). Last edit at 06/07/2011 06:40AM by Yanick Beaudet.
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