Langesundsfjord


Special thanks to my friends Frode Andersen and Svein A.Berge (Sandefjord), Ingulv Burvald and Alf-Olav Larsen (Stathelle), and Ragnar Salmén (Oslo) in Norway (also for borrowing from your publications) !


The Langesundsfjord in Norway is on the rim of an alkaline complex with its name being somewhat uncertain (the last being „LSF and the surrounding larvikite-area“). It is situated in the Oslo-region in the southern part of the Vestfold state about 130 km from Oslo (part of the complex, e.g. some famous islands and the Saga quarry area, extend into Telemark county). The Oslo-region is a rift-valley 280 to 230 mio years old, the southern part dominated by larvikite-rocks (used as an ornamental stone, e.g. UN-building in New York). Obviously there were multiple consecutive intrusions (10 ?) in the area. Besides the larvikites there are areas of glimmer-syenites and nepheline-syenites and to the north more granitic rocks. In the western part of the area, where the larvikite shows extended intrusions of nepheline-syenites, there are abundant veins of agpaitic nepheline-syenite pegmatites, mostly in a zone of of 4-5 km width.

During the 1800s there was a lot of mineral prospecting and collecting done on the islands, where the rock is extremely rich in pegmatites. Of interest was the thorium in several minerals, which was then used for lighting devices. With the development of light bulbes this small scale mining came to an end. Prof.Broegger was probably the most prolific person researching in this area. Still today you can sit and collect in small blast holes from his times, sometimes even in the pits of type localities. However, everything is heavily weathered today, but every now and then new outcrops turn up due to blasting for the construction of holiday huts on the islands.
On the main land rock production started as early as in the beginning of the 1800s, too, first by farmers using the rock from small quarries for construction. Commercial quarrying for decorative stone started in the late 1880s, first in the southwestern, later in the southern part of the area. For some time around the turn of the century some huge pegmatites were mined for feldspar. Today there are about 20 working larvikite quarries (and lots of abandoned ones), covering all the area with rock dumps, as only 5-10% or the rocks produced can be sold at about $ 0,80 per kilo.

On the main land collecting is possible not only in quarries, but also in roadcuts (the famous Bratthagen locality f.i.) and even in pegmatites outcrops in the woods (Bratthagen 2).

Several of the localities (e.g. Laaven, Skudesundskjaer, Bratthagen, Voera) are protected by law and collecting is strictly prohibited in some and heavily restricted (to picking up loose pieces at max) at others.

 

 

 

 

 

 

 

 

 

 

Mineral list (type locality = bold)
Actinolite
Aegirine 1834
Aegirine-augite
Aenigmatite
Albite
Allanite-(Ce)
Amesite
Analcime
Anatase
Ancylite-(Ce)
Andradite
Anglesite
Ankerite
Annite
Aragonite
Arfvedsonite
Arsenopyrite
Astrophyllite 1854
Augite
Azurite
Babingtonite
Baddeleyite
Barylite
Bastnaesite-(Ce)
Bavenite
Behoite
Berborite
Bertrandite
Biotite grp.
Boehmite
Bornite
Britholite-(Ce)
Bromellite
Calcioancylite-(Ce)
Calcite
Cancrinite
Cappelenite-(Y) 1885
Carbonatefluorapatite
Catapleiite 1849
Celadonite
Cerite-(Ce)
Cerussite
Chabazite
Chalcopyrite
Chamosite
Chevkinite-(Ce)
Chiavennite 1983
Chrysoberyl
Clinozoisite
Covelline
Cronstedtite ?
Datolite
Diaspor
Digenite
Diopside
Djurleite
Edenite
Elpidite
Ephesite
Epididymite
Epidote
Eudiaylite
Eudidymite 1887
Fayalite
Fergusonite-(Y)
Ferrimolybdite
Ferrocolumbite
Ferro-edenite
Fluroapatite
Fluorapophyllite
Fluorite
Gadolinite-(Ce) 1978
Gaidonnayite
Galena
Genthelvite
Gibbsite

Goethite
Gonnardite
Graphite

Grenmarite 2004
Grossular
Gypsum
Halloysite
Hambergite 1890
Hastingsite
Helvite
Hematite
Hemimorphite
Heulandite
Hilairite
Hingganite-(Y)
Hiortdahlite 1888
Hochelagaite
Homilite 1876
Hydrocerussite
Hydrozincite
Ilmenite
Kainosite-(Y)
Keldyshite
Laumontite
Lavenite 1885
Leadhillite
Leifite
Leucophanite 1840
Lizardite ?
Loellingite
Loparite-(Ce)
Lorenzenite
Magnesio-hastingsite
Magnesiokatophorite
Magnetite
Malachite
Melanocerite-(Ce) 1887
Meliphanite 1852

Microcline

Milarite
Mimetite
Molybdenite
Monazite-(Ce)
Montmorillonite
Mosandrite 1841
Muscovite
Natrolite
Nepheline
Nordenskioeldine 1887
Nordstrandite
Opal
Orthoclase
Paragonite
Parakeldyshite
Parisite-(Ce)
Pectolite
Perovskite
Perrierite

Petarasite
Pharmacosiderite
Phenakite
Phlogopite
Polylithionite
Polymignite 1824
Powellite
Prehnite
Pyrite
Pyrochlor 1826
Pyrophanite
Pyrrhotite
Quartz
Rhodochrosite
Riebeckite
Rosenbuschite 1887
Rutile
Schorl
Senaite
Serandite
Siderite
Sodalite

Sphaerobertrandite
Sphalerite
Stilbite
Stilwellite-(Ce)
Stilpnomelane
Sulfur
Tadzhikite-(Ce)
Taeniolite
Tetrahedrite
Thomsonite
Thorite 1829
Titanite
Tobermorite
Todorokite
Tremolite ?
Tritomite-(Ce) 1849
Tvedalite 1992

Vesuvianite
Wickmanite
Willemite
Woehlerite 1843
Wulfenite
Xenotime-(Y)
Zircon

My impression is that not enough work has been done for decades on the mineralogy of this area (lack of new descriptions between 1890 and 1978). Unfortunately there seems to be little tendency to collect and analyse very small minerals even today.

Again there has been an extremely interesting mineral symposium at the Kongsberg Musem in May 98.
Alf-Olav Larsen has continued his work on the „common“ species in the area. All the black mica, a.k.a. biotite or lepidomelane has turned out to be annite. It occurs in 2 generations, one from the magmatic phase, one from the hydrothermal phase.
Also Alf-Olav has done a reclassification of the black kalk-amphiboles due to the new 1997-nomenclature of the IMA. Most black amphibole is ferro-edenite (Langesundsfjord-Tvedalen area), some hastingsite and some magnesio-hastingsite (Hallevatnet-Larvik,Tjölling), one (Saga Pearl) edenite.
News:

8/97 large microcline-xx to 25 cm ! (Tuften ?)
large natrolite-xx w/pyrite and calcite-xx w/pyrite
large magnetite-xx to 10cm (Auen)
eudidymite-twins to 1cm (Vesle Aroeya, nothing new)
good hastingsite-xx in matrix, to 10cm (Saga Pearl)

in a sulfide paragenesis at Tuften: sulfur, cerussite, wulfenite, hemimorphite

A trip in july/august 1998 revealed nothing of interest - the large magnetites are as large as ugly (more the latter).
However, Frode Andersen has found taeniolite as a new mineral for the area in a classic locality on Siktesoeya (a few MMs only).
On the Kopparberg show in Sweden someone sold specimens of alleged fersmite - however, to all of us they look very much like being simple pyrochlore. X-ray is impossible, as the material is too tiny (at least what I have), and the allegedly performed chemical analysis is unable to differentiate between fersmite and pyrochlore.
In the area of the famous Saga quarry new operations have been started, moving into the old quarry from below. There are already many (uninteresting so far) pegmatites and therefore hope for the future. A new quarry is planned above Auen, that is between Saga and Thorbjoernsaas, which should be of interest, too.
The bad news is, that core drilling is now done to find and avoid areas rich in pegmatites.

I suppose I forgot to cite Alf-Olav´s work on the pyroxenes from 2 years ago: there is green (hydrothermal) aegirine, but most of what has been regarded as aegirine (dark-green to black) has turned out to be aegirine-augite (magmatic). To be true, the type-locality of aegirine (Laaven) only seems to have aegirine-augite !

By mid july 1999 there was nothing of higher interest yet so far - some meliphanite and hambergite coming out of Tuften. Alf-Olav identified graphite as a new mineral for the area, and there is a second taeniolite locality near Porsgrunn. A personal visit by the end of july revealed hardly anything, some loellingite and „calciothorite“. Nothing new or interesting from the above mentioned new operations.

Latest report as of april 2000:Nice natrolite from Treschow, thomsonite from Tuften, and quite lately nice chiavennite on aegirin-xx and analcime from Tuften. I'll take a look in june !
J
une 2000: Sparse rests of the chiavennite pegmatite left on dumps at Tuften (I got some), some nice fluoroapophyllite (2 gen.) at Saga Pearl. I visited the main land localities at Barkevika (of last century's fame - good collecting !), and went out with Alf-Olav Larsen to 2 Broegger classics (the eudidymite TL and the „weibyeite“-TL) and a newly discovered old blasting with nice catapleiite and enormous lots of eudialyte.
Speaking of eudialyte - Alf-Olav and Bob Gould have analysed 10 eudialytes from all over the area (fjord to Sandefjord) - and it is all „only“ eudialyte with virtually identical chemical composition - none of the new family members.
Correction 2003: Part of them are the new mineral ferrokentbrooksite, which wasn't known in 2000.
Our old favorite „Saga“ refuses to yield anything at all of interest.
Alf-Olav is working on a homepage on the area (and on a book, too). Expect a lot !

12/00: And here we go - here is the new homepage on the Langesundsfjord, run by my good friend and foremost Langesundsfjord specialist Alf-Olav Larsen: http://home.c2i.net/aolarsen

05/2002: A long break, but I only just returned to the area. In the last 1.5 years there have been not all too many finds. The reasons are manyfold, from cutting instead of blasting, core drilling to avoid pegmatites, to working in „wrong“ areas (Saga, Svensken1/Tuften). Thorbjoernsaas is gone - the old quarry with all of its boehmite, behoite and so on is covered by dumps from a new operation above, so far yielding nothing of interest. Finds have been made mainly in the easternmost part of Tvedalen, with the quarry formerly named Treschow-Fritzoe, now Almenninge, being most productive. But also adjactent quarries like Roeyaas and Oestskogen are interesting.
There have been many finds of natrolite in different habits, I saw short prismatic crystals, I would have thrown away as calcites, crust of needles covering feldspar-crystals, thick terminated crystals, some clear, some opaque.
Also in Treschow there have been very nice specimens with monazite-(Ce)-pseudomorphs after perfect hexagonal apatite crystals to 1cm long, some with natrolite-pseudomorphs after nepheline. With Frode Andersen we found perfect fresh bastnaesite-(Ce) crystals to 4mm, typically barrel-shaped and brown, along with nice micro-crystals of ancylite-(Ce). And most important of all: tvedalite has been found for the second time - on the lower levels of Treschow as small rosettes and balls on corroded helvite crystals - this time without chiavennite. Obviously only about 10 specimens have been found - one day only, the next day all was gone.
Well, and there are huge hambergites from Roeyaas, as well as (all new as of last friday) nice brown feldspar crystals with natrolite from the quarry to the left of Bjoerndalen (Arnt).
My main reason for going there was the 7th Kongsberg mineral symposium. For the area there was a most fascinating lecture of Frode Andersen and Svein Arne Berge on the Sandefjord localities (which I missed so far - a bad mistake to be corrected in summer !), along with 2 talks of Joe D.Grice on Canadian localities, Ole Johnsen on Narsarsuk as type locality, and A.Haugen/H.V.Ellingsen on about the same Greenland trip I took last year. Alf Olav Larsen this year has analysed the zeolites - all stilbite is stilbite-Ca, all heulandite is heulandite-Ca except for the Buer, Vesteroeya locality in Sandefjord, where it is heulandite-K. Definitely this symposium is worth a visit for anyone interested in Norwegian minerals (usually the talks are not so heavy on the alkaline side).

07/2002: Family vacation, 1 week at LSF. Nothing new in the quarries, though Knut Eldjarn reports 6cm homilite partings w/lmeliphanite and helvite from Haakestad.I searched the Sandefjord localities, but was about 20 years too late. Getting to the islands was difficult, but we finally made it and found a lot of hiortdahlite and eucolite as well as my best ever Vesle Aroeya eudidymite specimen. 3 weeks of heavy rain have their advantages in washing everything clean. What concerns the eucolite - you can see above that all eucolite is plain and simple eudialyte. However, some material found among others by me 20 years ago is said to have been analysed in Moscow and to have yielded kentbrooksite and ferrokentbrooksite, too. So all of my material will go to analysis (one sample each).

08/2003: 5 days in the area. Saga Pearl was fantastic - a pegmatite with chiavennite, tvedalite (3rd find to my knowledge) , and gadolinite-(Ce) as well as very nicely crystallised natrolite from another pegmatite. After about 10 years I returned to Vardeås - still hochelagaite and good gaidonnayite-crystals to 3mm. Svein-Arne and me found the „original block“. Otherwise nothing of interest – the great Tuften days are over.

12/2003: You know that Alf-Olav has analysed several eudialytes, I had all of mine analysed by EDS by Steffen Moeckel/in Moscow. The following table results. However, please be aware, that the 2 species are just a cutting edge apart, which makes the analyses difficult and not absolutely reliable, and obviously there are mixture crystals. As you see for some localities, there may be both, and I suspect even in the same crystal. In addition, all the EDS are done on one specimens each from my collection, so there may well be other results with other specimens. Anyhow - we seem to have a lot of ferrokentbrooksite in the area !
 

Locality

RDX

EDS

 Stokkøya E

 Eudialyte

 

 Eikaholmen

 Eudialyte

 Ferrokentbrooksite

 Vesle Arøya

 Eudialyte

 Eudialyte and Ferrokentbrooksite in different habits

 Arøyskjaer, Fredriksens Skjerp  E

 

 Ferrokentbrooksite

 Arøyskjaer, Fredriksens Skjerp  W

 

 Eudialyte

 Lille Arøya, Mosandrite Locality

 

 Eudialyte

 Lille Arøya, Bjerke

 

 Eudialyte in 3 different habits

 Risøya E

 

 Ferrokentbrooksite

 Risøya W

 

 Ferrokentbrooksite

 Nordholmen

 Eudialyte

 

 Siktesøya, Brønnebukta

 Ferrokentbrooksite

 Eudialyte

 Kjeøya

 

 Ferrokentbrooksite

 Barkevika

 Ferrokentbrooksite

 Ferrokentbrooksite

 Valleråsen

 

 Mixture of Eudialyte and Ferrokentbrokksite

 Saga, Tvedalen

 

 Ferrokentbrooksite

 Sagåsen

 Ferrokentbrooksite, Kentbrooksite, Zirsilite-(Ce)

 

 Bjørndalen, Tvedalen

 Ferrokentbrooksite

 

 Kariåsen, Sandefjord

 Ferrokentbrooksite

 Unclear, near Ferrokentbrooksite, under analysis

 Buer, Sandefjord

 Eudialyte

 Ferrokentbrooksite

 

7/2004:  Oh my...reports kept coming in from Tom Engvoldsen and Alf-Olav Larsen about the huge pegmatite in the new quarry below the old Saga, named either Sagåsen or Saga 3. So I went there thanks to Ryanair. There is a huge 1.5m pegmatite horizontally through all of the quarry, which is very similar to the famous Saga pegmatite. Indeed it may even be a faulted continuation of that one. It clearly is an agpaitic pegmatite, and it yielded and yields fantastic specimens of leukophanite, astrophyllite, tritomite (to 300 g!), ferrokentbrooksite and - yes ! - kentbrooksite among many others. The kentbrooksite is "more kentbrooksitic" than the type material from Greenland. Though there is little hydrothermal alteration, there are already specimens of berborite and behoite found. We definitely are back in the good times !

And speaking of Tom Engvoldsen - he's back on the scene, which means a very experienced and knowledgeabale, keen and thorough collector is roaming the localities again. And indeed - there is a new mineral he found, though back in his "old" collecting days in the late 80s:                                                                                     In any case it's worthwhile to visit his homepage: www.niob.no.

Otherwise we have found a new place with dm-large plates of pyrophanite in the lardalite area close to Lake Farris. Oh, and yes - it turned out that Svein-Arne and me have found literally hundreds of gaidonnayite and dozens of hochelagaite specimens at Vardeås last summer !

From the cappelenite locality on Vesle Aröya a new mineral is being published - the Zr-analogon of seidozerite. The name is obviously grenmarite. Publication is due in European Journal of Mineralogy, issue 6, 2004. It has been found in the 80s by Tom Engvoldsen. Jsut a few pieces - we all went looking at the Cappelen-pegmatite, but there's nothing there.

8/2005: What a boring region...nothing at all to be found - except for leftovers from the pyrophanite find form last year. There was nice hilairite in a neighbor quarry of Vardeås, but all gone, when I came there. And the weather did not allow for boating on the fjord, either.

8/2006: No better, nothing really new, some nice greenish meliphanite and an unknown gadolinite-group (?) mineral from Östskogen.

6/2007: Well, not a thrill. Some ancylite-mineral at Svensken 2. However, after all these years surprisingly nice finds on the islands - Svein and me seem to have been there last in the mid nineties... Secret good news from last autumn: Peter Andresen now lives in Skien and visits the quarries regularly - he found petarasite at Maleröd (or Midtberget?, not sure).

Back to main page.

Remember the link of Alf-Olav:
http://home.c2i.net/aolarsen

and of Tom:

http://www.niob.no

 

&Suggested reading:
Andersen, F., S.A.Berge, I.Burvald: Die Mineralien des Langesundsfjords und des umgebenden Larvikit-Gebietes, Oslo-Region, Norwegen, Mineralienwelt 7(1996), 4, 21-100 (in german)
Engvoldsen, T., F.Andersen, S.A.Berge, I.Burvald: Pegmatittmineraler fra Larvik ring-kompleks, STEIN 18(1991), 1, 15-71 (in norwegian)
Raade, G., J.Haug, R.Kristiansen: Langesundsfjord, LAPIS 5(1980), 10, 22-28 (in german)
Unfortunately enough there seems to be no comprehensive publication in english
Larsen A.O. et al.: Calcio-ancylite-(Ce) from syenite pegmatite at Tvedalen, Oslo Region, Norway. NEUES JAHRBUCH FUER MINERALOGIE-MONATSHEFTE, 9(2002), 411-423