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Larnite

Big Photo

Ettringer Bellerberg Mt., Ettringen, Mayen, Eifel Mts, Rhineland-Palatinate, Germany
© C.H.M.-Schäfer

Formula:
Ca
 
2
[SiO
 
4
]
System:MonoclinicHardness:6
Name:After the type locality, Scawt Hill, Larne, Co. Antrim, Northern Ireland, UK.
Dimorph of:Calcio-Olivine


Olivine Group. The high-temperature, monoclinic polymorph of Calcio-Olivine.

Larnite crystallizes at high temperatures. It occurs in limestones or chalk zones in contact with molten basaltic rocks. Larnite is stable in the range of 520° to 670° C; otherwise, it is only metastable at lower temperatures and inverts to its low-temperature polymorph, Calcio-Olivine, when shocked.

Classification of Larnite

IMA status:Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
Strunz 8th edition ID:8/A.07-30
Nickel-Strunz 10th (pending) edition ID:9.AD.05

9 : SILICATES (Germanates)
A : Nesosilicates
D : Nesosilicates without additional anions; cations in [6] and/or greater coordination
Dana 8th edition ID:51.5.1.1

51 : NESOSILICATES Insular SiO4 Groups Only
5 : Insular SiO4 Groups Only with cations in >[6] coordination
Hey's CIM Ref.:14.5.6

14 : Silicates not Containing Aluminum
5 : Silicates of Ca
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Type Occurrence of Larnite

Type Locality:Scawt Hill, Larne, Co. Antrim, Northern Ireland, UK
Year of Discovery:1929
Associated Minerals at type locality:
WollastoniteSpurritePerovskiteMerwiniteMelilite
Gehlenite

Occurrences of Larnite

Geological Setting:Metamorphosed sedimentary carbonate formations in contact with basaltic rocks.

Physical Properties of Larnite

Hardness (Mohs):6

Crystallography of Larnite

Crystal System:Monoclinic
Cell Parameters:a = 5.5Å, b = 6.74Å, c = 9.29Å
β = 94.59°
Ratio:a:b:c = 0.816 : 1 : 1.378
Unit Cell Volume:V 343.28 ų (Calculated from Unit Cell)

Optical Data of Larnite

Type:Biaxial (+)
RI values: nα = 1.707 nβ = 1.715 nγ = 1.730
2V:Calculated: 74°
Maximum Birefringence:δ = 0.023

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:High
Dispersion:r > v

Chemical Properties of Larnite

Formula:
Ca
 
2
[SiO
 
4
]
Essential elements:Ca, O, Si
All elements listed in formula:Ca, O, Si
Common Impurities:Al,Fe,Mg,Na,H2O,C,P

Relationship of Larnite to other Species

Common Associates:
WollastoniteSpurriteScawtiteRankinitePerovskite
MerwiniteMeliliteMayeniteKilchoaniteGrossular-Hibschite Series
GehleniteBrownmillerite
Related Minerals - Nickel-Strunz Grouping):
9.AD.05Calcio-Olivine
Ca
 
2
[SiO
 
4
]
9.AD.15Merwinite
Ca
 
3
Mg[SiO
 
4
]
 
2
9.AD.20Bredigite
Ca
 
7
Mg[SiO
 
4
]
 
4
9.AD.25Andradite
Ca
 
3
Fe
3+
2
[SiO
 
4
]
 
3
9.AD.25Almandine
Fe
2+
3
Al
 
2
[SiO
 
4
]
 
3
9.AD.25Calderite
(Mn
2+
 
,Ca)
 
3
(Fe
3+
 
,Al)
 
2
[SiO
 
4
]
 
3
9.AD.25Goldmanite
Ca
 
3
(V
3+
 
,Al,Fe
3+
 
)
 
2
[SiO
 
4
]
 
3
9.AD.25Grossular
Ca
 
3
Al
 
2
[SiO
 
4
]
 
3
9.AD.25Henritermierite
Ca
 
3
(Mn
3+
 
,Al)
 
2
[(OH)
 
4
|(SiO
 
4
)
 
2
]
9.AD.25Hibschite
Ca
 
3
Al
 
2
[(OH)
 
6-1
|(SiO
 
4
)
 
1.5-2.5
]
9.AD.25Hydroandradite
9.AD.25Katoite
Ca
 
3
Al
 
2
[(OH)
 
8-6
|(SiO
 
4
)
 
1-1.5
]
9.AD.25Kimzeyite
Ca
 
3
(Zr,Ti)
 
2
[(Si,Al,Fe
3+
 
)O
 
4
]
 
3
9.AD.25Knorringite
Mg
 
3
Cr
 
2
[SiO
 
4
]
 
3
9.AD.25Majorite
Mg
 
3
(Fe
2+
 
,Si,Al)
 
2
[SiO
 
4
]
 
3
9.AD.25Morimotoite
Ca
 
3
(Ti,Fe
2+
 
,Fe
3+
 
)
 
2
[(Si,Fe
3+
 
)O
 
4
]
 
3
 (?)
9.AD.25Pyrope
Mg
 
3
Al
 
2
[SiO
 
4
]
 
3
9.AD.25Schorlomite
Ca
 
3
(Ti,Fe
3+
 
)
 
2
[(Si,Fe
3+
 
,Fe
2+
 
)O
 
4
]
 
3
9.AD.25Spessartine
Mn
2+
3
Al
 
2
[SiO
 
4
]
 
3
9.AD.25Uvarovite
Ca
 
3
Cr
 
2
[SiO
 
4
]
 
3
9.AD.25Wadalite
Ca
 
6
(Al,Mg)
 
4
[Cl
 
3
|O
 
4
|{(Si,Al,Fe
3+
 
)O
 
4
}
 
3
]
9.AD.25Holtstamite
Ca
 
3
(Al,Mn
3+
 
)
 
2
(SiO
 
4
)
 
2
(OH)
 
4
9.AD.30Coffinite
(U,Th)[(OH)
 
4x
|(SiO
 
4
)
 
1-x
]
9.AD.30Hafnon
(Hf,Zr)[SiO
 
4
]
9.AD.30Thorite
(Th,U)[SiO
 
4
]
9.AD.30Thorogummite
(Th,U)[(OH)
 
4x
|(SiO
 
4
)
 
1-x
]
9.AD.30Zircon
Zr[SiO
 
4
]
9.AD.35Huttonite
Th[SiO
 
4
]
9.AD.35Tombarthite-(Y)
Y
 
4
[HSiO
 
4
]
 
3
9.AD.40Eulytine
Bi
 
4
[SiO
 
4
]
 
3
9.AD.45Reidite
Zr[SiO
 
4
]
Related Minerals - Hey's Index Grouping:
14.5.1Wollastonite
Ca[SiO
 
3
]
14.5.2Wollastonite-7T
14.5.3Wollastonite-2M
CaSiO
 
3
14.5.4Rankinite
Ca
 
3
Si
 
2
O
 
7
14.5.5Kilchoanite
Ca
 
3
Si
 
2
O
 
7
14.5.7Bredigite
Ca
 
7
Mg[SiO
 
4
]
 
4
14.5.8Hatrurite
Ca
 
3
[O|SiO
 
4
]
14.5.9Rosenhahnite
HCa
 
3
[Si
 
3
O
 
9
(OH)]
14.5.10Dellaite
Ca
 
6
Si
 
3
O
 
11
(OH)
 
2
14.5.11Afwillite
Ca
 
3
[HSiO
 
4
]
 
2
 · 2H
 
2
O
14.5.12Xonotlite
Ca
 
6
Si
 
6
O
 
17
(OH)
 
2
14.5.13Foshagite
Ca
 
4
[(OH)
 
2
|Si
 
3
O
 
9
]
14.5.14Hillebrandite
Ca
 
2
[(OH)
 
2
|SiO
 
3
]
14.5.15Jaffeite
Ca
 
6
[(OH)
 
6
|Si
 
2
O
 
7
]
14.5.16Suolunite
Ca
 
2
[H
 
2
Si
 
2
O
 
7
] · H
 
2
O
14.5.17Killalaite
Ca
 
3
[Si
 
2
O
 
7
] · 0.5H
 
2
O
14.5.18Okenite
CaSi
 
2
O
 
5
·2H
 
2
O
14.5.19Riversideite
Ca
 
5
Si
 
6
O
 
16
(OH)
 
2
·2H
 
2
O
14.5.20Trabzonite
Ca
 
4
Si
 
3
O
 
10
·2H
 
2
O
14.5.21Gyrolite
Ca
 
4
(Si
 
6
O
 
15
)(OH)
 
2
·3H
 
2
O
14.5.22Foshallasite
Ca
 
3
[Si
 
2
O
 
7
] · 3H
 
2
O(?)
14.5.23Tobermorite
Ca
 
5
Si
 
6
(O,OH)
 
18
·5H
 
2
O
14.5.24Clinotobermorite
Ca
 
5
[Si
 
3
O
 
8
(OH)
 
2
]2.4H
 
2
O - Ca
 
5
[Si
 
6
O17]·5H
 
2
O
14.5.25Nekoite
Ca
 
3
Si
 
6
O
 
15
·7H
 
2
O
14.5.26Plombièrite
Ca
 
5
Si
 
6
O
 
16
(OH)
 
2
·7H
 
2
O
14.5.27Jennite
Ca
 
9
H
 
2
Si
 
6
O
 
18
(OH)
 
8
·6H
 
2
O

Other Names for Larnite

Synonyms:
BeliteFelite
German names:
BelitBelithFelitLarnit
Russian names:
Ларнит
Spanish names:
BelitaFelitaLarnita

Other Information

Health Warning:No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Larnite

Reference List:Tilley, C.E. (1929) On larnite (calcium orthosilicate, a new mineral) and its associated minerals from the limestone contact-zone of Scawt Hill, Co. Antrim. Mineralogical Magazine, 22, 77-86.

American Mineralogist (1929): 14: 338.
(abstract).

American Mineralogist (1966): 51: 1766.

Jost, K.H., B. Ziemer, and R. Seydel (1977) Redetermination of the structure of dicalcium silicate. Acta Crystallographica: B33: 1696-1700.

Deer, W.A., R.A. Howie, and J. Zussman (1986) Rock-forming minerals, (2nd edition), v. 1B, disilicates and ring silicates, 248-255.

Internet Links for Larnite

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  • Raman and XRD data at RRUFF project
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  • Larnite details from Handbook of Mineralogy (PDF)
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    Localities for Larnite

    Hide Locality List
    The map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
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    (TL) indicates type locality. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
    Austria
     
    • Styria
      • Bad Radkersburg
        • Klöch
    		R. Exel: Die Mineralien und Erzlagerstätten Österreichs (1993)
    Germany
     
    • Rhineland-Palatinate
      • Eifel Mts
        • Daun
          • Üdersdorf
    		Schüller, W., Betz, V., Die Mineralien vom Emmelberg, Lapis 12/1986
        • Mayen
          • Ettringen
    		[Jasmund, K., Hentschel, G., Seltene Mineralparagenesen in den Kalksteineinschlüssen der Lava des Ettringer Bellerberges bei Mayen (Eifel), Beitr. Minera. Petr. 10, 296-314, 1964] [Lapis, 15 (5), 9-36]
    Israel
     
    Gross, S. (1977): The Mineralogy of the Hatrurim Formation, Israel. Geological Survey of Israel, Bulletin no. 70, 80 pp.
    Italy
     
    • Latium
      • Rome Province
    		Federico, M., Peccerillo, A., (2002): Mineral chemistry and petrogenesis of granular ejecta from the Alban Hills volcano, Mineralogy and Petrology, Vol 74, 223-252
    New Zealand
     
    • North Island
      • Northland
        • Kaipara
    		Mason, B. (1957): Larnite, scawtite, and hydrogrossular from Tokatoka, New Zealand. American Mineralogist 42, 379-392.
    Russia
     
    • Northern Caucasus Region
      • Kabardino-Balkarian Republic
        • Verkhnechegemskiy volcanic structure
    		A. E. Zadov data
    • Urals Region
      • Chelyabinsk Oblast'
        • Chelyabinsk coal basin
          • Kopeisk
    UK
     
    • Northern Ireland
      • Co. Antrim
        • Glenoe
        • Larne
    		Tilley, C.E. (1929) On larnite (calcium orthosilicate, a new mineral) and its associated minerals from the limestone contact-zone of Scawt Hill, Co. Antrim. Mineralogical Magazine, 22, 77-86.
    • Scotland
      • North West Highlands (Argyllshire)
        • Ardnamurchan
    		Handbook of Mineralogy - Anthony, Bideaux, Bladh, Nichols
    USA
     
    • Texas
      • Brewster Co.
        • Christmas Mts
    		Rocks & Minerals (1991): 66:3: 196-224.
      • Culberson Co.
        • Apache Peak area
    		Rocks & Minerals (1991): 66(3): 196-224.; Am Min 51:1766-1774
    Mineral and/or Locality
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