A serpentine-magnesite deposit quarried for magnesite and serpentine.

Now abandoned.

Note: the name Overntjern is often used for the quarry (Overngruve), although Overntjern is, in fact, a small, unmined serpentinite outcrop nearby (close to the track leading to the Overngruve).

Select Mineral List Type

Standard Detailed Gallery Strunz Chemical Elements

Commodity List

This is a list of exploitable or exploited mineral commodities recorded at this locality.

ⓘ Magnesite

Mineral List

11 valid minerals.

Detailed Mineral List:

ⓘ Althausite

Formula: Mg₄(PO₄)₂(OH,O)(F,◻)

Description: It is gray in color because of inclusions of magnetite and xenotime. It is also intimately associated with apatite. It occurs in cleavable masses up to several hundred grams and is altered to apatite along the cleavages.

References:

Raade, Gunnar, Tysseland, Magne (1975) Althausite, a new mineral from Modum, Norway. Lithos, 8 (3) 215-219 doi:10.1016/0024-4937(75)90038-9

Rømming, Christian, Raade, Gunnar (1980) The crystal structure of althausite, Mg₄(PO₄)₂(OH,O) (F,[]) American Mineralogist, 65 (5-6) 488-498

ⓘ 'Apatite'

Formula: Ca₅(PO₄)₃(Cl/F/OH)

Colour: brown

References:

Rømming, Christian, Raade, Gunnar (1980) The crystal structure of althausite, Mg₄(PO₄)₂(OH,O) (F,[]) American Mineralogist, 65 (5-6) 488-498

ⓘ Brucite

Formula: Mg(OH)₂

References:

Nordrum, Fred Steinar, Garmo, Torgeir T. (2006) Nyfunn av mineraler i Norge 2005-2006 [New finds of minerals in Norway 2005-2006]. Norsk Bergverksmuseum Skrift, 33. 56-62

ⓘ Clinochlore

Formula: Mg₅Al(AlSi₃O₁₀)(OH)₈

References:

Knut Edvard Larsen (2023) Collection.

ⓘ Clinochlore var. Leuchtenbergite

Formula: Mg₅Al(AlSi₃O₁₀)(OH)₈

References:

Knut Edvard Larsen (2023) Collection.

ⓘ Collinsite

Formula: Ca₂Mg(PO₄)₂ · 2H₂O

Description: As replacement of reddish althausite.

References:

Chopin, Christian, Ferraris, Giovanni, Prencipe, Mauro, Brunet, Fabrice, Medenbach, Olaf (2001) Raadeite, Mg7(PO4)2(OH)8: a new dense-packed phosphate from Modum (Norway) European Journal of Mineralogy, 13 (2) 319-327 doi:10.1127/0935-1221/01/0013-0319

ⓘ Dolomite

Formula: CaMg(CO₃)₂

References:

Witsø, Tor (1994) Sjelden dolomitt fra Overtjern. STEIN. Nordisk magasin for populær geologi, 21 (3) 193

ⓘ Enstatite

Formula: Mg₂Si₂O₆

References:

Rømming, Christian, Raade, Gunnar (1980) The crystal structure of althausite, Mg₄(PO₄)₂(OH,O) (F,[]) American Mineralogist, 65 (5-6) 488-498

ⓘ Hematite

Formula: Fe₂O₃

References:

Uwe Kolitsch (SXRD-analysis)

ⓘ Magnesite

Formula: MgCO₃

Habit: massive cleavages

Colour: white, pale pink

References:

Jøsang, Ottar (1966): Geologiske og petrologiske undersøkelser i Modumfeltet. Norges Geologiske Undersøkelse nr 235, 91-97

ⓘ Phosphoellenbergerite

Formula: (Mg,◻)₂Mg₁₂(PO₄,PO₃OH)₆(PO₃OH,CO₃)₂(OH)₆

References:

Knut Eldjarn

Nordrum, Fred Steinar (2000) Nyfunn av mineraler i Norge 1999-2000. Norsk Bergverksmuseum Skrift, 17. 59-63

ⓘ Pyrope

Formula: Mg₃Al₂(SiO₄)₃

References:

Nordrum, Fred Steinar, Garmo, Torgeir T. (2006) Nyfunn av mineraler i Norge 2005-2006 [New finds of minerals in Norway 2005-2006]. Norsk Bergverksmuseum Skrift, 33. 56-62

ⓘ 'Serpentine Subgroup'

Formula: D₃[Si₂O₅](OH)₄

References:

Jøsang, Ottar (1966): Geologiske og petrologiske undersøkelser i Modumfeltet. Norges Geologiske Undersøkelse nr 235, 91-97

ⓘ Talc

Formula: Mg₃Si₄O₁₀(OH)₂

References:

Anthony, John Williams, Bideaux, Richard A., Bladh, Kenneth W., Nichols, Monte C. (2000) Handbook of Mineralogy Vol. 4 - Arsenates, phosphates, vanadates. Mineral Data Publishing, Tucson, Arizona.

Gallery:

Mg₄(PO₄)₂(OH,O)(F,◻)ⓘ Althausite

Ca₅(PO₄)₃(Cl/F/OH)ⓘ 'Apatite'

(Mg,◻)₂Mg₁₂(PO₄,PO₃OH)₆(PO₃OH,CO₃)₂(OH)₆ⓘ Phosphoellenbergerite

List of minerals arranged by Strunz 10th Edition classification

Group 4 - Oxides and Hydroxides
ⓘ	Hematite	4.CB.05	Fe₂O₃
ⓘ	Brucite	4.FE.05	Mg(OH)₂
Group 5 - Nitrates and Carbonates
ⓘ	Magnesite	5.AB.05	MgCO₃
ⓘ	Dolomite	5.AB.10	CaMg(CO₃)₂
Group 8 - Phosphates, Arsenates and Vanadates
ⓘ	Althausite	8.BB.25	Mg₄(PO₄)₂(OH,O)(F,◻)
ⓘ	Phosphoellenbergerite	8.BB.55	(Mg,◻)₂Mg₁₂(PO₄,PO₃OH)₆(PO₃OH,CO₃)₂(OH)₆
ⓘ	Collinsite	8.CG.05	Ca₂Mg(PO₄)₂ · 2H₂O
Group 9 - Silicates
ⓘ	Pyrope	9.AD.25	Mg₃Al₂(SiO₄)₃
ⓘ	Enstatite	9.DA.05	Mg₂Si₂O₆
ⓘ	Talc	9.EC.05	Mg₃Si₄O₁₀(OH)₂
ⓘ	Clinochlore	9.EC.55	Mg₅Al(AlSi₃O₁₀)(OH)₈
ⓘ	var. Leuchtenbergite	9.EC.55	Mg₅Al(AlSi₃O₁₀)(OH)₈
Unclassified
ⓘ	'Serpentine Subgroup'	-	D₃[Si₂O₅](OH)₄
ⓘ	'Apatite'	-	Ca₅(PO₄)₃(Cl/F/OH)

List of minerals for each chemical element

H	Hydrogen
H	ⓘ Althausite	Mg₄(PO₄)₂(OH,O)(F,◻)
H	ⓘ Brucite	Mg(OH)₂
H	ⓘ Clinochlore	Mg₅Al(AlSi₃O₁₀)(OH)₈
H	ⓘ Collinsite	Ca₂Mg(PO₄)₂ · 2H₂O
H	ⓘ Talc	Mg₃Si₄O₁₀(OH)₂
H	ⓘ Phosphoellenbergerite	(Mg,◻)₂Mg₁₂(PO₄,PO₃OH)₆(PO₃OH,CO₃)₂(OH)₆
H	ⓘ Clinochlore var. Leuchtenbergite	Mg₅Al(AlSi₃O₁₀)(OH)₈
H	ⓘ Serpentine Subgroup	D₃[Si₂O₅](OH)₄
H	ⓘ Apatite	Ca₅(PO₄)₃(Cl/F/OH)
C	Carbon
C	ⓘ Dolomite	CaMg(CO₃)₂
C	ⓘ Magnesite	MgCO₃
C	ⓘ Phosphoellenbergerite	(Mg,◻)₂Mg₁₂(PO₄,PO₃OH)₆(PO₃OH,CO₃)₂(OH)₆
O	Oxygen
O	ⓘ Althausite	Mg₄(PO₄)₂(OH,O)(F,◻)
O	ⓘ Brucite	Mg(OH)₂
O	ⓘ Clinochlore	Mg₅Al(AlSi₃O₁₀)(OH)₈
O	ⓘ Collinsite	Ca₂Mg(PO₄)₂ · 2H₂O
O	ⓘ Dolomite	CaMg(CO₃)₂
O	ⓘ Enstatite	Mg₂Si₂O₆
O	ⓘ Hematite	Fe₂O₃
O	ⓘ Magnesite	MgCO₃
O	ⓘ Pyrope	Mg₃Al₂(SiO₄)₃
O	ⓘ Talc	Mg₃Si₄O₁₀(OH)₂
O	ⓘ Phosphoellenbergerite	(Mg,◻)₂Mg₁₂(PO₄,PO₃OH)₆(PO₃OH,CO₃)₂(OH)₆
O	ⓘ Clinochlore var. Leuchtenbergite	Mg₅Al(AlSi₃O₁₀)(OH)₈
O	ⓘ Serpentine Subgroup	D₃[Si₂O₅](OH)₄
O	ⓘ Apatite	Ca₅(PO₄)₃(Cl/F/OH)
F	Fluorine
F	ⓘ Althausite	Mg₄(PO₄)₂(OH,O)(F,◻)
F	ⓘ Apatite	Ca₅(PO₄)₃(Cl/F/OH)
Mg	Magnesium
Mg	ⓘ Althausite	Mg₄(PO₄)₂(OH,O)(F,◻)
Mg	ⓘ Brucite	Mg(OH)₂
Mg	ⓘ Clinochlore	Mg₅Al(AlSi₃O₁₀)(OH)₈
Mg	ⓘ Collinsite	Ca₂Mg(PO₄)₂ · 2H₂O
Mg	ⓘ Dolomite	CaMg(CO₃)₂
Mg	ⓘ Enstatite	Mg₂Si₂O₆
Mg	ⓘ Magnesite	MgCO₃
Mg	ⓘ Pyrope	Mg₃Al₂(SiO₄)₃
Mg	ⓘ Talc	Mg₃Si₄O₁₀(OH)₂
Mg	ⓘ Phosphoellenbergerite	(Mg,◻)₂Mg₁₂(PO₄,PO₃OH)₆(PO₃OH,CO₃)₂(OH)₆
Mg	ⓘ Clinochlore var. Leuchtenbergite	Mg₅Al(AlSi₃O₁₀)(OH)₈
Al	Aluminium
Al	ⓘ Clinochlore	Mg₅Al(AlSi₃O₁₀)(OH)₈
Al	ⓘ Pyrope	Mg₃Al₂(SiO₄)₃
Al	ⓘ Clinochlore var. Leuchtenbergite	Mg₅Al(AlSi₃O₁₀)(OH)₈
Si	Silicon
Si	ⓘ Clinochlore	Mg₅Al(AlSi₃O₁₀)(OH)₈
Si	ⓘ Enstatite	Mg₂Si₂O₆
Si	ⓘ Pyrope	Mg₃Al₂(SiO₄)₃
Si	ⓘ Talc	Mg₃Si₄O₁₀(OH)₂
Si	ⓘ Clinochlore var. Leuchtenbergite	Mg₅Al(AlSi₃O₁₀)(OH)₈
Si	ⓘ Serpentine Subgroup	D₃[Si₂O₅](OH)₄
P	Phosphorus
P	ⓘ Althausite	Mg₄(PO₄)₂(OH,O)(F,◻)
P	ⓘ Collinsite	Ca₂Mg(PO₄)₂ · 2H₂O
P	ⓘ Phosphoellenbergerite	(Mg,◻)₂Mg₁₂(PO₄,PO₃OH)₆(PO₃OH,CO₃)₂(OH)₆
P	ⓘ Apatite	Ca₅(PO₄)₃(Cl/F/OH)
Cl	Chlorine
Cl	ⓘ Apatite	Ca₅(PO₄)₃(Cl/F/OH)
Ca	Calcium
Ca	ⓘ Collinsite	Ca₂Mg(PO₄)₂ · 2H₂O
Ca	ⓘ Dolomite	CaMg(CO₃)₂
Ca	ⓘ Apatite	Ca₅(PO₄)₃(Cl/F/OH)
Fe	Iron
Fe	ⓘ Hematite	Fe₂O₃

Other Regions, Features and Areas containing this locality

Baltic Shield (Fennoscandian Shield)Shield

Eurasian PlateTectonic Plate

EuropeContinent

ScandinaviaRegion

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References

(n.d.)

Jøsang, O. (1966) Geologiske og petrologiske undersøkelser i Modumfeltet. Norges Geologiske Undersøkelse: 235: 91-97.

Rømming, Christian, Raade, Gunnar (1980) The crystal structure of althausite, Mg₄(PO₄)₂(OH,O) (F,[]) American Mineralogist, 65 (5-6) 488-498

Witsø, Tor (1994) Sjelden dolomitt fra Overtjern. STEIN. Nordisk magasin for populær geologi, 21 (3) 193

Raade, Gunnar (1999) Et unikt mineralselskap av magnesiumfosfater fra magnesitt -serpentin -forekomster på Modum [An unique mineral assemblage of magnesium phospates from magnesite-serpentine localities in Modum]. Norsk Bergverksmuseum Skrift, 15. 11-14

Nordrum, Fred Steinar (2000) Nyfunn av mineraler i Norge 1999-2000. Norsk Bergverksmuseum Skrift, 17. 59-63

Nordrum, Fred Steinar, Garmo, Torgeir T. (2006) Nyfunn av mineraler i Norge 2005-2006 [New finds of minerals in Norway 2005-2006]. Norsk Bergverksmuseum Skrift, 33. 56-62

Raade, Gunnar (2011) A metamict, thorium-rich magnesium phosphate from Overntjern, Modum, Norway. Norsk Bergverksmuseum Skrift, 46. 33-36

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Overntjern Quarry, Overntjern, Modum, Buskerud, NorwayiRegional Level TypesOverntjern QuarryQuarry (Abandoned) OverntjernLake ModumMunicipality BuskerudCounty (Former) NorwayCountry function showexplain() { $("#locexplain").toggle(); if (typeof movemap === "function") movemap(); }

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Commodity List

Mineral List

Detailed Mineral List:

Gallery:

List of minerals arranged by Strunz 10th Edition classification

List of minerals for each chemical element

Other Regions, Features and Areas containing this locality

References

Overntjern Quarry, Overntjern, Modum, Buskerud, Norway i
Regional Level Types
Overntjern Quarry Quarry (Abandoned)
Overntjern Lake
Modum Municipality
Buskerud County (Former)
Norway Country