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Magnetite

Posted by Rock Currier  
avatar Magnetite
November 11, 2010 12:30PM
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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?



Magnetite
Fe2+Fe3+2O4 Isometric

Magnetite on Albite, 5cm tall© 2003 John H. Betts

Magnetite on Albite, Cerro Huañaquino, Potosí Department, Bolivia 5cm tall

The name magnetite is apparently derived from the locality Magnesia, which borders on Macedonia. The ancient writers, Pliny and Nickander attribute the name to a person? named Magnes who on taking his herds to pasture found that the nails of his shoes and the iron ferrule of his staff stuck to the ground.

So far Mindat lists more than 9700 localities for magnetite and undoubtedly there are many more. Magnetite is one of the most abundant and commonly found oxides and is found under diverse geological conditions and sometimes in sufficient quantity to comprise an ore of iron. Magnetite is commonly found as grains in igneous rocks but most abundantly in the ferromagnesian types and at times as large segregated masses. Often these contain a lot of titanium in their composition due mostly to illmenite. Magnetite forms in the same conditions which form hematite and is usually if not always formed under conditions of high temperature. It it is found in the fusion crusts of meteorites and as dendritic forms in the mica of many localities and may be of secondary origin. It is also noted as a furnace product in slags and in sintered hematite ores. Brick, vitreous clay ware, and porcelain acquire a permanent magnetization parallel to the earths's magnetic field if magnetite crystals form during the firing. The largest deposits of magnetite are found in lens shaped masses in northern Sweden in Archaean rocks

A strong indicator that you may have magnetite is to see if it is attracted by a magnet and by checking its streak which is black. Maghemite, another strongly magnetic iron oxide, is brown to bluish black and can easily be confused with magnetite. However, unlike magnetite, it transmits light in thin splinters and has a brown streak. Hematite for which Magnetite is occasionally mistaken has a dark red streak and is not attracted by a magnet. Heating magnetite to 550 degrees C however alters the mineral to hematite and causes loss of its magnetic property. Magnetite alters to limonite and to hematite. Magnetite pseudomorphs after pyrite, chlorite minerals, anatase, talc, dolomite, chalcopyrite, siderite, and serpentine are known. Presumably all of these may be found not completely altered and containing the originative mineral and magnetite as well. So if you get a reaction to a magnet from a mineral, it may also not be a pure mineral, but partly magnetite. At some few localities, magnetite possesses polarity and this magnetite is given the variety name of lodestone. This means that the magnetite will act as a natural magnet. This natural magnetism can sometimes be enhanced by placing it in a strong magnetic field.

Magnetite crystals are most commonly found as octahedrons, but is also found in dodecahedrons with striated faces and more rarely as cubes. Sometimes octahedral forms of magnetite are altered to hematite and this is common enough that they are given the varietal name of martite (hematite, var. martite). Sometimes pure masses of twinned magnetite are found and when broken along its parting planes forms crystals that are sometimes mistaken for crystals of magnetite but are in reality just parting forms of twinned magnetite. The magnetite from Port Henry, New York example these. The cleavage of untwinned magnetite is not distinct.

The literature on magnetite and hematite is extensive and not something we want to go into here. Much of what is above was taken from Dana's/Ford text and Dana's system 7th edition, V1, P698-705 which has a nice summary of information about magnetite.

Historically, the most sought after crystals by collectors were perhaps those from Switzerland. Recently however the new find of good octahedral magnetites from Cerro Huañaquino, Bolivia and especially the new brilliant cubic magnetites from Balmat, New York, USA have displaced the Swiss specimens as the most desired. However, you can look at good examples of all of these and more in the picture gallery below and make up your own mind.
[Rock Currier 2010]


Magnetite
Afghanistan
Nangarhar Province (Ningarhar Province), Khogyani, Marki Khel
Nangarhar Province (Ningarhar Province), Speen Ghar

Magnetite3.7cm tall© Dan Weinrich
Magnetite 2.1cm tall© Rob Lavinsky

The one on the left above is from Marki Khel, and the one on the right from Speen Ghar. It would appear that both of these specimens are very likely from the same locality and at the very least we hope someone can help sort out what these two locality names represent when it comes to the specimens from them.


Magnetite?!!!
Argentina
Mendoza, Altiplano de Payún Matru, Payún volcano

Magnetite?!!! 4.5cm wide© Rockpick Legend Co.
Magnetite?!!! 10.3cm tall© Fabre

Specimens like this from Payún volcano are usually labeled Hematite after Magnetite and many more and much better examples are shown under Hematite in the Mindat Gallery and the Best Minerals Hematite article. It is possible that these specimens have still retained their magnetic character and that is why they are currently labeled magnetite. It is also possible, and perhaps even likely that these specimens have been mislabeled and are really now Hematite. Many collectors and some dealers really don't pay much attention to the accuracy of the labels they receive with their specimens or generate themselves and don't take the time to run even the simplest of tests on their specimens to determine if perhaps the labels may be in error. In fact they don't even know how. As time passes and you learn more and gain more experience you will see more and more errors on labels and will learn to look specimen labels with a more critical and analytical eye. We need more of this kind of person here on mindat to help clean up the mistakes and errors that exist here on Mindat.
"Although these specimens are usually labelled "Payun" or "Payun Matru" volcano, this is actually in a rather extensive volcanic field with dozens of vents, and exactly which fissures these crystals came from has understandably not been revealed by the prospectors who dig them, and there are at least two localities for them in this area, so "Payun Matru region" or just "Altiplano de Payun Matru" might be a more honest locality designation, leaving off the volcano name. As is obvious from the crystal habits, these started out as magnetite, although the majority have oxidised to hematite and should now be labelled "hematite pseudomorphs after magnetite". A minority are still magnetite, or only partially replaced. Magnetite and hematite crystals, often skeletal, deposited from the gas phase in volcanic fumaroles by hydrolysis of iron chloride vapour are fairly common in high-temperature volcanic fumaroles worldwide, but these argentine examples are by far the largest and finest fumarolic magnetites known." - Alfredo Petrov, 2010.


Magnetite
Australia
Northern Territory, Harts Ranges (Hartz Ranges), Mud Tank

Magnetite 3cm wide© JSS


This is a popular collecting spot, mostly for large zircon crystals, in a carbonatite. It was being mined for Vermiculite recntly, with collectors allowed to fossick on the dumps still. The magnetite crystals can be large, but are seldom completely intact.


Magnetite
Australia
Queensland, Biggenden Shire, Biggenden Mine (Mount Biggenden Mine; Biggenden Gold And Bismuth Mine; Mount Biggenden Bismuth Mine; Mount Biggenden Magnetite Mine; Biggenden Quarry)

Magnetite 9cm wide© G. van der Veldt


This site was a large magnetite mine, in a skarn deposit. It was a popular spot for collecting until the mine closed some (20?) yrs ago, and specimens are rarely seen now.


Magnetite
Australia
South Australia, Flinders Ranges, North Flinders Ranges, Arkaroola area, Sitting Bull area

Magnetite 5.4cm wide© Rob Lavinsky


A popular collecting area with various small iron, copper, fluorite and uranium deposits related to granite intrusions, but good specimens are rarely seen.


Magnetite
Australia
Tasmania, Hampshire district, Kara Mines, Kara #1 Pit

Magnetite, Andradite etc 15cm wide© R. Bottrill 2006


An operating open-cut mine, located 40 km south of Burnie in northwestern Tasmania, producing magnetite and minor scheelite. It is the only presently operating mine in a series of related skarn deposits associated with Devonian granites intruding Ordovician limestones. The pit contains a zoned magnetite-andradite-hedenbergite-vesuvianite-epidote skarn, which contains minor scheelite and molybdenite and calcite veins with various Cu, Pb, As, Zn, Bi sulphides, fluorite and some Be minerals. Famous for excellent andradite specimens and many other interesting minerals. Magnetite is very common, often in well formed dodecahedral crystals, to about 5cm, but are typically a little dull in lustre. They may be coated in other crystallised minerals, including bavenite, fluorite, calcite, andradite, epidote, tremolite and helvite-danalite.
[Ralph Bottrill 2010]


Magnetite
Austria
Salzburg, Hohe Tauern Mts, Stubach valley, Totenkopf Mt. (incl. Lower Riffl glacier)

Magnetite & Actinolite ~9cm wide©



Magnetite
Austria
Tyrol, North Tyrol, Ziller valley, Schlegeis valley (Schlegeisgrund), Furtschaglkar

Magnetite 16.5cm wide©



Magnetite
Azerbaijan
Daşkəsən (Daskasan; Dashkyasan) District, Dashkesan, Dashkesan (Dashkezan) Co-Fe deposit

Magnetite 8cm tall© 2001 John H. Betts
Magnetite 10cm center© 2001 John H. Betts


Magnetite & Calcite 5.3cm wide© Fabre Minerals
Magnetite & Calcite 11.9cm wide© Rob Lavinsky


Magnetite 10cm tall© Terry Burtzlaff
Magnetite 5cm tall© Dan & Diana Weinrich Minerals


Magnetite & Fluorapatite 6.0cm© Weinrich Minerals
Magnetite 12cm wide© Dan Weinrich


Magnetite
Bolivia
Potosí Department, Cerro Huañaquino

Magnetite 3.3cm wide© Rob Lavinsky
Magnetite 6cm wide© Rob Lavinsky


Magnetite 5.5cm tall© Rob Lavinsky
Magnetite 12.5cm tall© Rob Lavinsky


Magnetite 5cm tall© Rob Lavinsky
Magnetite 6.3cm wide© Rob Lavinsky


Magnetite 8.6cm wide© Rob Lavinsky
Magnetite 8.4cm wide© Rob Lavinsky


Magnetite 4.1cm wide© JSS
Magnetite 12.3cm wide© Rob Lavinsky


Magnetite 6cm wide© 2003 John H. Betts
Magnetite 5cm wide© www.redcrystalshop.com


Magnetite 10.4cm tall© Rob Lavinsky
Magnetite 13.1cm wide© Rob Lavinsky

As you head north out of Potosi, the main highway for a distance passes by Cerro Huañaquino. If you look up at that point you can see little prospects scratched on the side of the mountain a few hundred feet up, and this is the locality that has produced all the recent specimens of Magnetite from Bolivia. Several thousand of them have been produced and sold to the collector market. Some of the specimens are surprisingly good and may rank among the best Magnetites found anywhere. On many specimens the magnetite crystals are growing on tiny crystals of albite.


Magnetite
Brazil
Minas Gerais, Jequitinhonha valley, Diamantina\

Magnetite 4.2cm wide© Rob Lavinsky
Magnetite 4.8cm wide© Rob Lavinsky


Magnetite
Canada
Nova Scotia, Annapolis Co., Hampton

Magnetite 3.5cm wide© Maggie Wilson


John Sinkankas notes in his Mineralogy that small, beautifully crystallized magnetite crystals occur in the Triassic trap rocks of Kings and Annapolis counties.


Magnetite
Canada
Nova Scotia, Kings Co., Bay of Fundy, Amethyst Cove (Captain Kidd's Cove)

Magnetite 3.1cm wide© Maggie Wilson



Magnetite
Canada
Ontario, Hastings Co., Bancroft District, Faraday Township

Magnetite ~6cm wide©
Magnetite ~5cm tall.© Danny Jones

John Sinkankas notes in his Mineralogy that a single crystal from this locality weighed in at more then 400 pounds.


Magnetite
Chile
Antofagasta Region, El Laco

Magnetite 12.9cm wide© Rob Lavinsky



Magnetite
Cuba
Oriente Province, Firmeza District, Juragua Iron Co. Mines

Magnetite 4.5cm tall©



Magnetite
Czech Republic
Bohemia (Böhmen; Boehmen), Ústí Region, Krušné Hory Mts (Erzgebirge), Klášterec nad Ohří, Měděnec (Kupferberg)

Magnetite 6.5cm wide© Barry Flannery



Magnetite
France
Midi-Pyrénées, Aveyron, Decazeville, Firmi, Puy de Wolf (Puech de Voll)

Magnetite on serpentine 8cm wide© Patrice Cmolik



Magnetite
Germany
Baden-Württemberg, Odenwald, Eberbach, Katzenbuckel Mt., Michelsberg Quarry

Magnetite 25cm wide© Volker Betz


The Magnetite (Titanomagnetite) from Katzenbuckel are crystals up to 3cm but most of the crystals found were only a few mm. At this location the magnetite crystals are frequently oxidized to Maghemite. They are still magnetic, but the streak changes from black to brown. If etched with cold 30 % HCl this pseudomorphed crystals give a white residue of Leukoxene ( Anatase) while with the real Magnetite the black Ilmenite inclusions remains. The locality is of the European Province with unusual peralkaline dyke rocks. This location was first metioned by Leonhard in 1822 for Nepheline and is located about 35 km E of Heidelberg. With a very long list of papers until today. A milestone of petrography/ petrology research ( Rosenbusch). The quarries were operated from about 1900 to 1974, the locality is now a geotop. The crystals are not free standing but found covered by natrolite, but the crystals are easy to clean because of alteration of the rock. The magnetite specimens were abundant for a short time (1966 to 1973). Since that time collecting is almost impossible as the zone that was productive of the magnetite crystals is flooded. I think only a small number has been distributed, but one of the best magnetites in Germany. There are better specimens than the one pictured here
[Volker Betz 2010]


Magnetite
Germany
Bavaria, Lower Bavaria, Bavarian Forest, Zwiesel, Bodenmais, Silberberg Mine

Magnetite 5cm wide© Rob Lavinsky



Magnetite
Germany
Rhineland-Palatinate, Eifel Mts, Mendig

1.37mm Magnetite xl on matrix© Chinellato Matteo



Magnetite
Germany
Saxony, Glauchau, Callenberg

Magnetite 10cm wide© Thomas Witzke
Magnetite 11.1cm wide© Rob Lavinsky


Magnetite
Italy
Campania, Naples Province, Somma-Vesuvius Complex, Monte Somma, Ercolano, San Vito, San Vito quarry

1.22mm Magnetite xl on Diopside© D. Preite - M.C.
1.23mm Magnetite xl with Diopside© Chinellato Matteo


Magnetite
Italy
Lombardy, Sondrio Province, Malenco Valley

2.11mm group of Magnetite xls© Chinellato Matteo
Magnetite 4.5cm wide© Martins da Pedra


Magnetite
Italy
Lombardy, Sondrio Province, Malenco Valley, Lanterna Valley

Magnetite 10cm tall© Maxminerals



Magnetite
Italy
Lombardy, Sondrio Province, Malenco Valley, Lanterna Valley, Campo Franscia, Franscia Mine

1.7 mm Magnetite cluster© Chinellato Matteo
Magnetite on matrix 11 cm wide© Maxminerals


Magnetite
Italy
Piedmont, Torino Province, Canavese District, Chiusella Valley, Traversella, Traversella Mine

Magnetite 6.2cm wide© Rob Lavinsky
Magnetite ~8cm wide© Chinellato Matteo


Magnetite
Italy
Piedmont, Torino Province, Canavese District, Léssolo, Cálea, Brosso Mine

Magnetite & Pyrite 16cm wide©
Magnetite & Pyrite 6cm wide© Rui Nunes 2008


Magnetite & Pyrite 12cm wide© Carles Millan



Magnetite
Japan
Honshu Island, Chubu region, Nagano prefecture, Kuryu mine

Magnetite FOV 4.2cm© R. Tanaka



Magnetite
Mexico
Chihuahua, Mun. de Aquiles Serdán, Santa Eulalia District

Magnetite on Quartz ~6cm tall©



Magnetite
Mexico
Durango, Mun. de Durango, Cerro de los Remedios, Victoria de Durango, Cerro de Mercado Mine

Magnetite & Fluorapatite ~8cm wide©
Magnetite 5cm wide© Rob Lavinsky

The magnetites from this locality are not particularly outstanding, but when they occur with sharp yellow sometimes transparent apatite crystals, I must admit that I find I become more interested in them.


Magnetite
Morocco
Meknès-Tafilalet Region, Khénifra Province, High Atlas Mts, Tamazeght complex, Bou-Agrao Mt.

Magnetite 6.2cm wide© Rob Lavinsky
Magnetite 6.3cm wide© Rob Lavinsky


Magnetite
Morocco
Souss-Massa-Draâ Region, Ouarzazate Province, Tazenakht, Bou Azzer District, Bou Azzer

Magnetite 4cm wide©



Magnetite
Mozambique

Magnetite 42cm wide© Arliguie M


The only locality we have for this specimen is Mozambique, but the thing is huge and a deposit that produces things like this must produce other note worthy specimens. I hope someone can eventually tell us more about this locality and its specimens. The crystals on this specimen must be nearly as big as your fist and the thing must weigh well over 100 pounds.


Magnetite
Namibia
Erongo Region, Usakos and Omaruru Districts, Erongo Mountain

Magnetite 7.9cm wide© Rob Lavinsky



Magnetite
Norway
Nordland, Hattfjelldal

Magnetite on matrix ~3cm wide© AÖ 2010



Magnetite
Norway
Telemark, Porsgrunn, Mørje, Auen( Blue Pearl) Quarry

Magnetite 2,5cm©
Hematite after Magnetite. 6,2 cm wide© Ingulv Burvald

Auen is one of the many larvikitie quarries in this area. Larvikite is quarried as a dimension stone and is widely used as countertops and claddings. The commercial grade larvikite consist predominantly of blue or black schillerizing feldspar.
The larvikite was formed as igneous plutons during Permian (+/- 300mill years ago) rifting in the Oslo graben in southeastern Norway. These igneous plutons are host to numerous alkaline pegmatites carrying many rare minerals.

The magnetite at Auen was found in one of these pegmatites in 1996. The actual pegmatite was severly altered, with a clay mineral, albite covered microcline and magnetite as main minerals. Small zircon, molybdenite sheets and a yellow, transparent mineral was present as accessory minerals. Most of the magnetite was partly altered to hematite
The magnetite crystals reached almost 10 cm across and often had quite complex crystal shapes. The best specimen I found was a 15cm wide cabinet specimen consisting of three intergrown magnetite crystals. This specimen is now on loan to Agder Naturmuseum in Kristiansand. The magnetite was abundant in this material, and several truck loads of material were available just after the pegmatite was exposed, and magnetite could still be found in the quarry a few years after the initial exposure of material.
[Olav Revheim 2010]


Magnetite
Pakistan
North-West Frontier Province, Mansehra District, Naran-Kaghan Valley, Sapat Gali (Soppat; Suppat; Sumpat; Sumput)

Magnetite & Forsterite (peridot) 2cm tall© TVM
Magnetite & Forsterite (peridot) 9cm wide© Kuno Stoeckli


Magnetite & Forsterite (peridot) 3.8cm tall© TVM
Magnetite & Forsterite (peridot) 3.3cm tall© TVM


Magnetite & Forsterite (peridot) 6cm wide© H. Obodda


Magnetite crystals growing with gem grade peridot crystals? Every collector would love to have one of these. But the association was not common and for every thousand peridot crystals there may have been one specimen with this association.


Magnetite
Russia
Far-Eastern Region, Primorskiy Kray, Olginsky District, Olga Bay

Magnetite ~9cm wide©



Magnetite
Russia
Northern Region, Murmanskaja Oblast', Kola Peninsula, Kovdor Massif, Kovdor Mine

Magnetite 7.5cm wide© Arliguie M



Magnetite
Russia
Northern Region, Murmanskaja Oblast', Kola Peninsula, Kovdor Massif, Zheleznyi Mine (Iron Mine)

Magnetite & Calcite 3.9cm tall© Rob Lavinsky



Magnetite
b]Russia[/b]
Urals Region, Southern Urals, Chelyabinsk Oblast', Zlatoust, Nazyamskie Mts, Akhmatovskaya Kop' (Achmatovsk Mine)

Magnetite & Clinochlore 11cm wide© Kevin Ward



Magnetite
South Africa
Northern Cape Province, Aggeneys

Magnetite & Chalcopyrite 7cm wide© Rob Lavinsky



Magnetite
Spain
Extremadura, Badajoz, Burguillos del Cerro, Milucha Mine

Magnetite 7.5cm tall© Angel Acedo
Magnetite 14cm wide© Angel Acedo
Magnetite 8.5cm wide© Angel Acedo


Magnetite
Sweden
Värmland, Filipstad, Nordmark (Nordmarksberg)

Magnetite & Calcite 10cm wide© 2000 John H. Betts



Magnetite
Switzerland
Wallis (Valais), Binn Valley

Magnetite & Adularia 2.7cm wide© Rob Lavinsky



Magnetite
Switzerland
Wallis (Valais), Binn Valley, Lercheltini (Lärcheltini) area

Magnetite 5cm wide©
Magnetite ~7cm wide©


Magnetite, xl on left ~4cm©



Magnetite
USA
Arkansas, Hot Spring Co., Magnet Cove, Perovskite Hill

Magnetite 2.6cm tall©


At one time magnet cove was famous for specimens of massive magnetite specimens that acted as natural magnets. They were rated in quality by the size of the nails they could pick up. The 16 penny grade would pick up 16 penny nails and the ten penny quality would pick up the larger ten penny nails (those that sold ten for a penny). The most highly sought after material was the spike grade material that would actually pick up a small railway spike.
[Rock Currier 2010]


Magnetite
USA
California, Fresno Co., Wright Mountain area, Christie Mine (Christi Mine; Christy Mine)

Magnetite & Dolomite 2.7cm tall© Michael C. Roarke



Magnetite
USA
California, San Benito Co., Diablo Range, New Idria District

Magnetite on matrix 3.9cm wide© Rob Lavinsky



Magnetite
USA
California, San Benito Co., Diablo Range, New Idria District, Santa Rita Mine (Union Carbide Nuclear; Santa Rita Asbestos Mine; Joe 5 pit; Joe 7-5 Mine)

Magnetite ~8cm wide©



Magnetite
USA
Idaho, Lemhi Co., Spring Mountain District

Magnetite on Ludwigite 5.3cm wide© JSS
Magnetite 4.3cm wide© John Sobolewski


Magnetite 4.2cm tall© JSS



Magnetite
USA
New Jersey, Hudson Co., Secaucus, Laurel Hill (Snake Hill; Penetentiary Quarry

Magnetite 4cm wide© 2001 John H. Betts
Magnetite 8.8cm wide© Frank A. Imbriacco III


At Laurel Hill, magnetite veins are common. Perfect specimens are not easy to come by, due to weathering and brittleness. Good specimens are obtained, when vein walls are composed of soft chlorite. Excellent splendent crystals were observed suspended as individuals and groups in the mountain leather variety of actinolite. Their color coal-black; crystallizing as octahedrons or penetrating (spinel) twins; up to 3 cm on an edge and associated with albite, sphalerite, pyrite, bornite, chalcopyrite, allanite, epidote, orthoclase, and quartz.
[Facciolla, N. (1981) Minerals of Laurel Hill, Secaucus, New Jersey, privately published book involving only this locality]


Magnetite
USA
New Jersey, Sussex Co., Franklin Mining District, Sterling Hill

Magnetite ~15cm wide©



Magnetite
USA
New Mexico, Grant Co., Fierro, Hanover-Fierro District, Continental No. 2 Mine

Magnetite 2.3cm wide© Rob Lavinsky



Magnetite
USA
New Mexico, Grant Co., Hanover-Fierro District, Republic Mine

Magnetite 5cm wide© FL Murray



Magnetite
USA
New Mexico, Socorro Co., Jones District

Magnetite 5cm wide© FL Murray



Magnetite
USA
New York, Essex Co., Port Henry

Magnetite 2.7cm wide© Rob Lavinsky
Magnetite xls, label is ~5cm wide© 2007 Peter Cristofono


Magnetite, big xl is ~12cm©
Magnetite, xl on right is ~4cm©
Magnetite ~5cm wide©

These were at one time quite common among collectors in the north eastern part of the United States, but now are seldom seen. The bottom three images show not terminated crystals of magnetite, but rather parting forms that have been broken from massive twinned magnetite.


Magnetite
USA
New York, Putnam Co., Southeast Township, Brewster, Tilly Foster mine

Magnetite & Clinochlore ~12cm wide©
Magnetite 3cm wide© 2001 John H. Betts

The magnetite and clinochlore specimen pictured above is about as good as this association gets from this mine.


Magnetite
USA
New York, St Lawrence Co., Balmat-Edwards Zinc District, Balmat

Magnetite 5.8cm wide© Rob Lavinsky
Magnetite 4.2cm wide© Rob Lavinsky


Magnetite 7.2cm wide© Rob Lavinsky
Magnetite 11.9cm wide© Rob Lavinsky


Magnetite 9.2cm wide© Rob Lavinsky
Magnetite 5.5cm wide© Rob Lavinsky

The magnetite specimens from this mine have been around for a few years, but because of their brilliance and relatively cubic shape, they have a new standard of quality that other localities find difficult to match. The best from this locality are truly world class for the species.


Magnetite
USA
Pennsylvania, Berks Co., Morgantown, Grace Mine

Magnetite 5.5cm wide© M.Heintzelman



Magnetite
USA
Pennsylvania, Chester Co., Warwick Township, St. Peters, French Creek Mines

Magnetite 6.8cm wide© M.Heintzelman

There are better specimens of magnetite than the one pictured here and we will add one or more of them as soon as possible.


Magnetite
USA
Vermont, Windsor Co., Chester, Carlton Quarry (Carleton Quarry)

Magnetite ~7.5cm wide©



Click here to view Best Minerals M, click here to view and here for Best Minerals A to Z and here for Fast Navigation of completed Best Minerals articles.

Rock Currier
Crystals not pistols.



Edited 32 time(s). Last edit at 03/26/2012 10:36AM by Rock Currier.
Re: Magnetite
November 29, 2010 03:48PM
    
Rock,

Please see below.

Olav


Magnetite
Norway
Telemark, Porsgrunn, Mørje, Auen( Blue Pearl) Quarry

Magnetite 2,5cm©
Hematite after Magnetite. 6,2 cm wide© Ingulv Burvald

Auen is one of the many larvikitie quarries in this area. Larvikite is quarried as a dimension stone and is widely used as countertops and claddings. The commercial grade larvikite consist predominantly of blue or black schillerizing feldspar.
The larvikite was formed as igneous plutons during Permian (+/- 300mill years ago) rifting in the Oslo graben in southeastern Norway. These igneous plutons are host to numerous alkaline pegmatites carrying many rare minerals.

The magnetite at Auen was found in one of these pegmatites in 1996. The actual pegmatite was severly altered, with a clay mineral, albite covered microcline and magnetite as main minerals. Small zircon, molybdenite sheets and a yellow, transparent mineral was present as accessory minerals. Most of the magnetite was partly altered to hematite
The magnetite crystals reached almost 10 cm across and often had quite complex crystal shapes. The best specimen I found was a 15cm wide cabinet specimen consisting of three intergrown magnetite crystals. This specimen is now on loan to Agder Naturmuseum in Kristiansand. The magnetite was abundant in this material, and several truck loads of material were available just after the pegmatite was exposed, and magnetite could still be found in the quarry a few years after the initial exposure of material.



Edited 2 time(s). Last edit at 11/29/2010 07:17PM by Rock Currier.
avatar Re: Magnetite
November 29, 2010 07:21PM
Olav,
I have made a few tweaks to the formatting of your suggested addition to the magnetite article. Click on the edit button at the bottom of your post and you can see the code adjustments that I made. Note that in the second image, the code string I changed the left to center which gives it a little space between the images. I also adjusted the pixel size a little to line the pictures up. It looks good now.

You are a moderator in the best minerals group, why don't you go ahead and copy the whole thing into the magnetite article in the appropriate place?

What do you want to work on next? or perhaps you are already working on something.

Rock Currier
Crystals not pistols.
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